Especially a trip that ends up revealing secret KGB investigations, decapitated corpses, a curious box of contraceptives and the true fate of a Chinese war hero chosen to succeed Mao Zedong.

Then again, few storylines melded fact and fable more than the life – and particularly, the demise – of Marshal Lin Biao.

Anthony Grey, a British novelist, turned his hand at speculating what had become of the Chinese communists' most capable commander in The Chinese Assassin.

Grey took a few liberties about how Lin had come to die in a plane crash on the remote Mongolian steppe in 1971 and what happened next. He had little choice given the closed nature of the countries involved – China, Mongolia and the Soviet Union – at the time of his writing in 1978 and their ready use of propaganda.

Still, I was intrigued by many of the novel's details that had some basis in reality. Geography and timing were also in my favour.

By then it was 1992 and I was the only full-time western correspondent in Mongolia. While I was happy reporting the latest news from Tartary, such as the withdrawal of the last Russian troops from the country or election of the first non-communist President, finding out what really happened to Lin became an obsession.

Lin had been a famous commander both against the Japanese invaders and later as head of the Fourth Field Army that routed the Chinese Nationalists during the civil war which raged from the end of 1945 until 1949. After fading into obscurity to deal with multiple health issues, Lin was later handpicked by Chairman Mao to head the army and elevated to be his anointed successor during the chaos of the Cultural Revolution.

Then, all of a sudden, Lin disappeared, with China declaring him a traitor who had died in Mongolia while trying to flee to arch-enemy, the Soviet Union. The Soviets and their client state Mongolia said little.

And so two decades on from the crash, historical puzzles were ripe for another crack. Mongolia was now one of the most welcoming nations anywhere for journalists, the USSR had collapsed and even China – Tiananmen turmoil notwithstanding – was also opening up.

Among my first tasks was to find the crash site. As typical for steppe travels, we pointed the Russian jeep – in this case towards the eastern town of Onderkhaan - and asked herders for directions as we bumped along dirt tracks and forded rivers.

Nearing our goal, we found locals who had scavenged chunks of the plane to fashion into sturdy cookware over the years. Later we collected our own keepsakes of twisted aluminium that would later confound customs officials hoping for an impost.

A guide also showed us the low, unmarked mound where eight men and one woman had been buried.

Over the ensuing months, my trusty translator Enkhbat would help me locate and interrogate dozens of people connected to the crash and Lin. The research net would eventually stretch from California to Taiwan.

Some were interviewed in a secluded cove on the mezzanine floor of the UB Hotel, a refuge for mining sharks, big game hunters, "lords of poverty" aid chiefs, cross-dressing environmentalists and spooks. Others were traced to their yurt (or "ger" as the Mongolians call their mushroom-shaped tents) in far-flung parts of the country.

Guards recalled seeing the plane alight as it came down, flames streaming from its tail. A senior policeman even said it had turned around near the Soviet-Mongolian border – and was heading back towards China when it crashed. Russian counterparts would later support a claim that rankles in China to this day.

Evidence was mixed about the identity of the men on board the plane, with only ID found for the marshal's son, Lin Liguo.

The emerging quandary, though, related to the sole woman. Lin and his wife Ye Qun had gone missing in 1971, at which time she would have been 50.

But Mongolians who visited the crash site in its immediate aftermath described the female as being much younger than that. And, in a bizarre twist that I learned from Mongolia's deputy foreign minister in 1992, a packet of contraceptives had been recovered from the woman's possessions.

If the woman was not Ye, then perhaps Lin was not on board – so the logic went. Intrigue was mounting.

My probe, meanwhile, had turned up high-level interest from the KGB. A crack team, I learnt, had flown in from Moscow weeks after the crash to exhume the corpses not once but twice.

During the first exhumation, the team singled out the oldest-looking man and the woman, severing their heads from the decomposing corpses. One Mongolian guard told of his job boiling the skulls in a big pot to remove skin and hair, with a colleague joking: "Is the soup ready yet?"

Weeks later, the KGB returned. A photo marking a celebration after their second exhumation, complete with roasted ram washed down with arkhi, the local rocket fuel disguised as vodka, revealed the key personnel I would need to find in Russia.

So Enkhbat and I headed to Moscow in search of an army pathologist named Vitali Tomilin and his shadowy KGB colleague.

We squatted in the apartment of a Russian journalist from Astrakhan, a Caspian Sea city home to people claiming ancient links to Mongolia. One night we were visited by the leader of a Caucasus republic who placed his loaded pistol on the coffee table while his bodyguard waited by the door.

Each trail turned cold until we traced Tomilin, now semi-retired, to a riverside institute. He agreed to meet – but only if the successor spy agency to the KGB approved.

Leads in America also beckoned, so I took an Aeroflot flight to New York for a rendezvous in Central Park with Zhang Ning, briefly Lin Liguo's fiancee.

Zhang described the final frantic hours within the Lin household in their seaside villa not far from Beijing.

Fearing an imminent purge by Mao, the son and wife had panicked, dragging the marshal, drowsy from medication, to a hastily prepared plane waiting at a nearby airstrip. Lin's daughter Doudou warned Beijing two hours before the flight but the centre's leaders did nothing.

And what about contraceptive pills, I sheepishly asked?

Blushing, Zhang said Lin had forced himself on his wife some time before. Liguo had plied Ye, not yet at menopause, with Hong Kong-made prophylactics to calm fears she might fall pregnant if it happened again.

However, a new twist had emerged. The marshal, while avowedly a communist, had been making - so it seems - secret contacts with the very Nationalists he was fighting.

This plotline was delivered by a retired ex-chief of defence intelligence ("J2") would had fled the mainland along with Generalissimo Chiang Kai-shek and the remnants of his deflected armies to Taiwan at the end of the Civil War. The J2 chief now lived in Los Angeles, so off I headed there.

Chiang, so I was told, was convinced Lin so distrusted Mao that he was ready to switch sides. The spy chief had personally handled a couple of secret overtures believed to have come from Lin. The first had been made in late-1945, before the civil war erupted.

And so, Taiwan was added to the itinerary, via a brief visit to Washington to explore CIA leads.

However, Moscow now beckoned. Tomilin was ready to chat, along with his KGB partner, retired colonel-general Alexander Zagvozdin.

They revealed their investigation had personally been ordered by Soviet leader Leonid Brezhnev and KGB chief Yuri Andropov. "Usually an investigator does not sign his own report," Zagvozdin said, sharing his secrets for the first time. "But I was so excited that I did – together with [Tomilin]."

Their conclusion: Lin and Ye had indeed died in a plane that had not been shot down. Evidence – some of which they gave me – included a rare photo of Lin without a cap, showing a deep scar on his head, a photo of Lin's skull recovered in Mongolia revealing the same gash, snaps of Lin and Ye's decomposing bodies, and an odd souvenir – a charred toilet paper sign in Chinese taken from the plane.

The second exhumation was needed because Soviet records showed Lin had had tuberculosis. A telltale hardening of the lung had to confirmed from the now-headless corpse. "We found it there on exactly the same spot on the right lung," Tomilin told me.

The nine bodies, as I was to I learn from Mongolians, were of no further use, so they were trucked to outside Ulaanbaatar, cremated in oil drums and the ashes poured into nine bags and handed over to the Chinese embassy. (China to this day claims the bodies remain buried on the steppe.)

They also declared the plane had been warned not to enter Soviet air space by anti-aircraft troops.

That part of the plot finally settled, it was back to Mongolia to check my flat next to the children's theatre-cum-stock exchange was still intact, tie up loose ends, and prepare for trips to Beijing and Taiwan.

Later, my visit Lin's Beidaihe villa and nearby Shanhaiguan airport would feel positively conspiratorial, coinciding with the centenary of Mao's birth, Boxing Day 1993.

Then to Taiwan, to locate a former agent who was J2's chief in Hong Kong, and an academic who backed claims the only time President Chiang had been known to have wept was on learning of Lin's likely death – dashing his dream of returning to the mainland.

Soon after I would publish my findings in articles and broadcast interviews, stirring debate inside China that echoes to this day. I would later visit Lin's home town in Huanggang in central Hubei province to understand where his story began.

By now it was time for me to get on with other, more prosaic reporting that would have me based in China, Singapore, Japan, and for the past decade, Australia. The chapter on the marshal and me was closed – for now.

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