And now, in time for Christmas, the return of Australia's most beloved kelpie – albeit without Koko, the original star, who moved too soon to a higher plane in 2012.

The original film was a phenomenon, with $21 million at the Australian box office. More than that, it earned a place in the national dreaming, alongside The Castle and Darryl ('Tell 'im 'e's dreamin') Kerrigan, with whom the red dog  shares many characteristics. Both battlers, both er, dogged about doing what's right, both blessed with an irrational loyalty to loved ones, both modest (and in Darryl's case, much to be modest about).

There were significant differences as well: The Castle stood firmly against change, big government and 'progress'; Red Dog stood firmly for those things, being set in the frontier mining towns of the Pilbara, where Australia's fortune was being made. People came and went, but the red dog represented constancy and community. He tied people together.

Sequels are always difficult, and the challenge is in proportion to the achievements of the original. You have to find an idea that's just as strong but not the same. That goes for the dog and the cast too. Finding the dog is probably the easier part: dogs are incapable of bad acting.

It's no surprise then that the prequel falls short. There's just enough to remind us of the charms of the original but less than we need to repeat the enjoyment. The new story is less compelling, its construction more mechanical and episodic. What's even stranger, it's not really about the dog. The first was not a children's movie, but the second is much more squarely aimed at kids. That makes it sappier, softer and less fearless. There are marketing paw prints all over it. Why would you cast Jason Isaacs – fine actor that he is - as the father? His part is not really necessary, unless you want a name English actor to help reach a British audience.

The film opens in Perth in 2011, with a heavy-handed wink. A busy father (Isaacs) who has not been paying attention to his family must take his two boys to the movies. They see 'some dog movie' – the original Red Dog – and the tears flow. Elder son Theo (Zen McGrath) asks dad to explain. We flash back to 1968 when Michael (Levi Miller) arrives at his grandfather's cattle station near Karratha in the Pilbara. The boy, wearing a tie, is a city softie. Grandpa (Bryan Brown) is harsh, not wishing to discuss the family crisis back in Sydney. 'Who else was gonna take ya?'

The colours of this part of Australia are glorious, but not this glorious. Everything has been tweaked, the digital pudding overegged. Young Mick takes to the life with gusto: he learns to ride a trail bike and his grandpa employs a helicopter pilot who's been in Vietnam (Thomas Cocquerel). One of the Aboriginal kids (Calen Tassone) teaches Mick about the dreaming, and there's a colourful Chinese cook who always carries an umbrella (Kee Chan). In short, more life and adventure and culture than the boy has ever experienced. After a cyclone, there is also a puppy covered in blue mud who quickly becomes a boy's best friend.

So far, so good. The elements are appealing, and actors like Brown and Kelton Pell and Justine Clarke lend safe hands. Kriv Stenders, who directed the original, has good comic instincts and we know he can handle dogs. Once the puppy grows up, the new kelpie played by Phoenix shows all the tools: athleticism, speed, great eyes and a willingness to work.

So what went wrong? In a word, self-conciousness. Like the over-coloured landscapes, there is too much of everything: jokes that push too hard, emotions that arrive by telegraph, a 'spiritual' Aboriginal sub-plot that labels the script as right-on and worthy. In the first film we followed a dog who had lost his master; in the second, we follow the kid and the dog through all the typical adventures you would find in an Aussie kids film of the 1950s: bush fires, dust storms, black magic, even a dangerous horse. The simplicity and beauty of the original is gone. Instead we get hijinx and visual effects and god help us, comical voice effects from the dog. Innocence made the original; lack of it destroys the sequel/prequel.