This is it. Crunch time. The acid test. The big show. The moment of truth. The proof of the pudding. The one day in September. It's time to find out which of the three remaining MasterChef hopefuls will find glory and honour, and which will live their lives in shame forever more. Over the course of this 18-hour grand final episode, we will discover just which of these talented oven-switcher-onners has what it takes to make dreams come true.

We begin with a heartwarming trip down memory lane, reminding us of how far we've come and what we've learnt along the way. Remember when Gary knocked on a yellow door? And when George forced Emma to hug him? Remember that moment when we weren't sure whether we liked Kelty or not, right before he opened his mouth for the first time? Remember how Heston Blumenthal made some stupid thing or other? Remember when everyone cried?

We remember all this and more, but perhaps what we remember most of all is the greatest lesson of MasterChef: don't make a freaking birthday cake, Liliana.

The actual action tonight begins with the familiar opening sequence, in which the contestants' happy faces now seem grimly ironic. We then go to the sun, which is rising, in the day's first big surprise. At the MasterChef house, the finalists are getting dressed. “I don't know how we did it,” says Emma, in agreement with thousands of viewers, as she wanders around a field and cuts some weeds or something. We reminisce about Emma's food journey, in which she has consistently made edible dishes and managed a rate of approximately one intelligible word in two out of her mouth.

Lynton is also getting prepared, and saying he entered the competition for his sister, once again demonstrating his almost otherworldly inner beauty, which perfectly matches his otherworldly outer beauty. Will he win MasterChef? Perhaps? Has he already won Master Of Our Hearts? Yes. Just look at his eyes, people. Seriously.

Then there's Samira, who looks nostalgically back over her food journey, in which she has already proven herself inadequate. She also looks back nostalgically at herself reading a book. An omen? Shall she go on to read a book again? Only time will tell.

The cars pull into the driveway. The music swells. Outside kitchen headquarters sits the ominous red scooter, a silent testament to the dreadful fate of its anonymous owner. As the finalists walk inside, all the eliminated contestants applaud and cheer from the balcony, where they will stand throughout the finale offering useless advice and ruining the cooks' concentration. “Look around you,” Gary says, and shows them three sets in which have been set up fake restaurants resembling the ones the finalists wish to establish. At least I think that's what's going on: it's also possible he's threatening them in some way.

“The future is up to you,” Gary says with a straight face. George informs them that there will be three rounds, with the lowest score dropping out of the competition. The winner will “become part of a very elite club”, George says, confusing “elite” with “small”.

“Only perfection will do,” says Matt, even though he is well aware that this is not true – all you have to do is be slightly better than the other two. In fact, “perfection” is less the goal than “crap plus one”.

They are off and running, into the pantry to gather ingredients for the first round. “I've been waiting for this my whole life,” says Lynton, who is finally achieving his lifelong ambition to run around with a shopping basket on a shiny hardwood floor. We then cut to an ad for The Bachelor, to remind us that whatever we think of the MasterChef contestants, dignity is relative.

Back in the kitchen, Lynton reveals that everything that was said before the break still applies. Thank god for consistency. He also reveals that his mother was a rubbish cook and he resents the negative influence she has had on his life. Also at this point we stop and ask some serious questions about George's bow-tie and what it says about contemporary Australia.

Lynton promises George and Gary that he will cook his steak medium rare. Big mistake Lynton: you want to claim your right to silence when asked how you're going to cook a steak.

Meanwhile Samira is cooking salmon: at the start of the competition she hated fish, but she's grown to love it, to understand it, to think how a fish thinks. She is the Aquaman of MasterChef. Also she's cooking sous vide, which is how everyone cooks everything now, at least if there's no liquid nitrogen available.

And Emma is cooking chicken I think. It's a bit hard to make out, but it looks like a chicken. She's been practising all week, and we can only admire just how much great food has been wasted by these people as they practised their dishes before the finale.

With an hour to go, a flustered Emma rushes to her bench with a jug full of urine: the pressure is beginning to tell. Evidence of her mental frailty is seen in the fact that she has put a cabbage in the oven and then turned the oven off. On the bright side, this means she won't be cooking cabbage.

Matt angrily demands to know why Lynton isn't cooking his steak normally. “You know, it's funny Matt,” says Lynton, but fails to live up to this boast.

“Time and time again, something little trips me up,” Lynton frets, darkly alluding to the likelihood that George will physically attack him before the day is out.

“Cook like the world is watching!” cries George, in a bitingly sarcastic comment on the ratings. This is a good moment to observe Samira putting olive oil in mayonnaise and then throwing it out – her behaviour is becoming increasingly erratic. “I don't know what to do,” says Samira, a revelation that would've been more helpful before she entered the competition.

Oh God that moment when the Bachelor doesn't kiss that girl! So awkward, right?

Back in the kitchen, Samira is not impressed with her salmon skin. She should have used Pro-Activ. She is so angry at her salmon skin that she begins banging pans with no apparent aim. Meanwhile Emma realises that her burnt cabbage is not going to work, and she might have to just have a steamed cabbage not work instead. Also her chickens haven't had long enough to rest, and are at risk of nodding off at the wheel.

Up on the balcony people are clapping like a bunch of stupid seals, as Samira fondles her salmon unsettlingly. She wants something green on her plate. She considers sneezing, but decides to go get some herbs instead.

Time is up, and Samira begins leaping around like a psychotic flea, as Pip screams incoherently from the balcony, enraged at the fact that these inferior fools are there instead of her. They've all done very well, inasmuch as none of them is actually dead yet.

Time to taste, and Samira's salmon is “spectacular” according to George, but then he's a man who thinks that jacket was a good choice. The salmon, it would seem, was pleasant.

Up steps Lynton, and the balcony erupts in applause for the man we all love. Matt thinks he's done himself proud in terms of presentation, which comes across as a little patronising. The judges eat, and Matt says, “Today might be your day”, and our hearts sing. Apparently Lynton has given them sweetness and saltiness and silky smoothness and little pops and really what else could you want?

Emma's turn, and she is disappointed that her dish is not perfect. This would be a fatal flaw if the assertion that it had to be perfect was in any way accurate. Gary thinks it's beautiful cooking. “There's a lot going on here,” says George, either complimenting her or accusing her of a conspiracy.

The finalists stand before the judges to hear the axe fall. “Three spectacular dishes,” George winces through gritted teeth. What George liked about Samira's salmon was the salmon – a good sign. Gary agrees but George gave her a nine and Gary gave her an eight, illustrating the deep divisions within the judging team. What Gary loved about Emma's dish was the gutsy, honest flavours – a nice change from the lying cowardly flavours we've all seen up to now. Again, George and Gary disagree on scores – will they never be friends again? And then there's Lynton: what Matt liked about Lynton's dish was “everything” – 10 out of 10! And 10 from George! And 10 from Gary! Finally his food has scored as highly as his dreamy smile, and his 30/30 leads Samira and Emma, both on 26, going into the second round.

Cut to commercial, and Masterfoods asks, “Why cook when you can create?” A good question: what is the point of all this rubbish?

“What a fabulous start to the finale,” Gary exclaims with much too much enthusiasm to be believed. He assures us that in MasterChef, “anything can happen”, but this is patently not true – nobody's ever going to be eaten by a shark in the kitchen, for example.

Up on the balcony, Christina gazes down with deeply felt loathing as it is revealed that the finalists in round two must run the dream restaurants we were shown earlier. They must cook with chicken, a food which Australians apparently eat far too much of every year.

“I'm ready for a service challenge: bring it on!” cries Samira, unconvincingly. From above the eliminees call out encouragement with absolutely no sincerity whatsoever. Lynton reveals that south-east Asian cooking is his dirty little secret. I don't know what this means – is he doing something perverted with satay?

“You can do this,” calls Liliana, but how would she know? Samira is sprinkling little specks of stuff on her chicken. She has no idea what she's doing. Meanwhile Emma is boasting about leaving bones in chicken, like that's a skill. Matt subtly suggests to her that she's an idiot, but she is extremely invested in the idea of leaving bones in so people have to get their hands filthy to eat.

George observes that Emma is falling apart. Gary observes that Lynton appears to be in control, but it looks more like he's slowly losing consciousness. Samira is talking smack about Lynton's puree: the judges said he made a great puree, and Samira thinks she makes the best puree of all, and her puree today is going to be fantastic. We gain a strong impression of what a casual conversation with Samira would be like.

Jules is freaking out about Emma, who is the vessel for Jules's vicarious lust for glory. Emma is stressed, worrying about those bones. The bones are very important, so she decides to make things difficult for her customers and stick with them.

Meanwhile Samira has decided to cook her chickens perfectly, in yet another illustration of her nose for strategy. As the customers file in, we wonder whether it will be her strategy of doing things perfectly, Emma's strategy of making things hard to eat, or Lynton's strategy of filling the building with smoke, that will prevail.

We take a breather for that Nando's ad where the son and his parents have lunch and nothing makes sense and you want to stab them, and then back to the kitchen, where the skills on show are actually approaching a Nando's-esque level of expertise.

Customers are sitting down and getting liquored up in preparation for the storm to come. “Two chicken,” George calls to Lynton, as if there is anything else on the menu. Why people are being forced to put in orders at all is an utter mystery. “The waitress comes over,” says Emma, “and I have to remember to tell her everything.” The waitress doesn't really care though, and can't understand what Emma is saying anyway. Emma has detailed instructions for how to eat her dish, which is sure to please all the diners – everyone loves food that comes with orders from the chef. Samira's instructions are “eat with love”, which will probably irritate the customer even more.

The diners seem to be enjoying Emma's chicken gratin, and the complex challenge of breaking open her potato. Once you open the potato, there's … a potato inside. It's like the world's dullest Kinder Surprise.

Less surprising is Lynton's chicken salad, which pleases his diners apart from the woman who says it could have been a bit warmer. It's not supposed to be warm you dumb moo. The judges enjoy his salad but are disappointed the chicken is cold – they wouldn't be saying that if they knew the hardship of a Top End summer on horseback. Can't they see what Lynton has been through?

Samira's diners love her dish, but the pumpkin puree is cold, a disaster which Lucy comments on as if she would've done any better. What Matt loves about it is that the chicken is cooked beautifully, but dislikes the pumpkin puree being cold. He doesn't like it when one part of a dish is hot and one is cold, even though that is exactly what he wanted Lynton to do.

“I've just done my first service in my own restaurant,” says Emma happily, fundamentally misunderstanding the nature of what has been going on.

Judging time rolls around, and Samira confides that she has never been so afraid in all her life, making it clear just what a luxurious, privileged existence she has led up to now. She is near tears as Matt slams her puree without mercy. She only gets 22 out of 30, and up above Rishi applauds smugly, revelling in her distress. Lynton has also disappointed with his cold chicken, and gets only 21 out of 30, because these judges are cruel and devoid of human feeling. However this means Lynton is through to round three, and up above Rishi applauds some more, happy that there is still a chance that Samira might be dead in the water.

Finally, Emma's turn, and though the judges don't say anything bad about her dish, their scores are pretty similar to Samira's, because all thoughts of fairness and objectivity have been abandoned in the dead-eyed lustful chase for sensation. But she gets one point more, and she's through to round three, and Samira is out for the second time this season, and Rishi is absolutely ecstatic.

“So, do you think you know what's coming?” asks Matt, his eyes gleaming like a man who has just released a venomous snake into the room. Round three is a pressure test, news that causes everyone to react with surprise and amazement even though it's not even vaguely surprising. Matt then talks for about half an hour about the guest chef who will be setting the final challenge, and then reveals it's Ben Shewry, who I believe is a cook of some kind.

“Without giving anything away, how much does this dish mean to you?” George asks Ben – why he doesn't want to give anything away is a mystery given they're about to just tell them what it is anyway. Ben lifts the cloche, and reveals … the new address that has Australia begging for more: Wonderland!

Actually, several minutes later it turns out that the final dish is a small wooden box, which looks attractive but frankly would probably lack flavour. Inside the box is something called “the flight of the bees”, which is a thing that looks like a beehive but is actually a big pile of random fruit and vegetables and meringue and cream and stuff with a picture of a beehive on top of it. It looks extremely complicated and not worth the effort, but by this stage both Emma and Lynton are thoroughly indoctrinated and lack the will to tell Ben to get stuffed.

“The whole thing's a frigging pressure point,” says Jules, with needless vulgarity and even more needless audibility – nobody asked her as far as I can remember.

They have two hours to make the bee thingumajig – the three judges will be joined by Ben, making the final round's score out of 40. “This round's an incredibly important round,” says Emma, which clarifies things a lot.

Firstly they make their meringues. George yells at them because that's his thing. Emma begins talking to herself. Jules tells us what's important in a meringue, like she's the frigging meringue comptroller or something. Emma feels like she's falling behind, but only because she is. “You need to be busy little bees,” shouts Gary, because he hates life.

Lynton and Emma are doing very complex things with blenders and herbs and saucepans and things and it's all very confusing and not really worth it when you consider that you could just buy some ice-cream and it'd be just as good. They have to put something called granita in a freezer – I used to eat granita biscuits but I think this is a different thing.

Matt observes that when Ben gets nervous he develops little bumps. Whatever, man. Ben thinks they're being very slow: he is disgusted that these amateur cooks are dragging their feet on the dish he as a seasoned professional full-time chef took a year and a half to invent.

Up above the watchers notice that Emma isn't following the recipe. Ben goes over to Emma's bench to destroy her confidence by pretending it matters what order she dropped the ingredients into what looks like a big pan full of old dishwater.

On the balcony Faiza calls encouragement, reminding us of her ability to speak. Lynton is slicing his pumpkin (not a euphemism) and pushing himself as hard as he can (a euphemism). But his pumpkin slices are too thick and he must start his element again and Emma is using the slicer and everything is going crrrrrrazy! For the next 10 minutes, Lynton recites a list of the things that Emma does, and then he does also. It's absolutely riveting. Rishi commentates the action, biting back his fury at the fact he's not there.

Disaster strikes as Lynton over-whips his cream (possibly a euphemism). Luckily, Emma also over-whips her cream, despite Rishi's repeated entreaties – that will teach her to train her brain to block out the sound of Rishi's voice. “It's become an absolute footrace,” says Lynton, misleadingly. Jules chips in with commentary on the meringues – “Lynton gets his out and it's quite soft,” she says – wa-hey! However, the meringue discrepancy evens out because Emma's granita is too hard. Will hard granita defeat soft meringue? Only time will tell, but time is running out, and everyone is counting down, and the pressure has reached the point at which we must simply be consumed by fire.

It's time to taste these bizarre concoctions, and god only knows what a mess they're going to make of them. Lynton puts his together, and gets it done “in the nick of time”, in keeping with every single other dish made throughout the year. He brings it to the judges and promptly falls asleep, still managing to answer the judges' questions.

The tasting happens, and Ben immediately begins picking at it like a picky McPickerson. The flavours are good, apparently, which is always a bad sign for the cook's chances. The meringue is too soft and the grated apple is too sparse and some other pedantic rubbish.

Emma puts hers together and is really happy with how it's gone – another bad sign. She's a bit worried about her granita, which has been quite moody lately. Also her pumpkin sticks to the mould and tears a little bit, so she basically might as well just serve up a wheelie bin full of used nappies.

She brings her boxes to the judging room, where Gary pretends that she's a lot more interesting than she really is, and they all notice the tear because they're just obsessive-compulsive madmen. But they still enjoy it – “my palate is salivating”, George gibbers like some kind of idiot – and inspirational music plays and makes it pretty obvious who's won this thing. But before we're told officially, time for one more fireball and a few more shots of the Bachelor grinning like a serial killer.

And so time to announce the winner, and the suspense levels haven't been this high since we were wondering which stupid Nando's ad was going to be on next. Back in the kitchen, the judges emerge, as what sound like the opening chords of Children of the Revolution play and everyone gathers around to see who will win that weird trophy thing.

But before we announce the winner, obviously, we need to hear Gary talk some nonsense, and have people clap, and introduce the finalists' families, and hug, and cry, and clap some more, and cry some more, and then George talks some crap, and music plays, and dear God this is taking DAYS. All the families take their turn to talk, and then Gary tells everyone what just happened as if we didn't already know. And now, FINALLY, it's time for the scores. Gary explains that the cook with the highest score wins – suddenly it all makes sense.

First, Lynton, whose meringue was soft and grated apple was insufficient. Gary gives him seven, which means he's screwed. George gives him eight, which means he's still pretty much screwed. Matt gives him eight, saying “your dish was the best-presented”, in a shameless piece of misdirection. “It was a really great first effort,” says Ben patronisingly, and gives him a seven. Lynton could not be more screwed.

Emma's turn. Gary gives her a nine, and it's all over. Shut the gate. The rest is pointless. George gives her nine. Geez. Matt objects to the torn pumpkin, but gives her a nine, the damn liar. And Ben gives her nine and she's won, and Lynton, apparently the world was never meant for one as beautiful as you.

And that's it. Emma is MasterChef 2013, and the exhilarating, mildly diverting rollercoaster ride is finished for another year. All that is left to discover is what brand of cleaning fluid Emma will be promoting, and we await 2014, when the format will be freshened up by giving all contestants sidearms.