In a plot worthy of a spy novel, the downfall of high-flying Chinese politician Bo Xilai began when a British businessman was found dead in a hilltop hotel room.

The scandal that subsequently unfolded in Chongqing, a steamy riverside megacity, saw Bo's police chief flee to a US consulate and his wife convicted of murder, and finally brought Bo's own political aspirations to an ignoble end.

Chongqing, in China's southwest, has thick clumps of skyscrapers and an urban population of more than 16 million, swollen each day by opportunity-seekers arriving from the countryside.

Projects spearheaded by Bo, who became the city's leader and one of China's top 25 politicians in 2007, are everywhere, from rows of low-cost apartments to new bridges and a massive light-rail system -- all part of his attempt to gain political momentum to catapult him even higher within the power structure of the Chinese Communist Party.

Winding roads lead to the Lijing Holiday Hotel atop a forested hill. There, in one of a series of villas with sweeping views of Chongqing's high-rise city centre, Bo's wife Gu Kailai is said to have poisoned Briton Neil Heywood.

A steady stream of wealthy visitors dine on steak and yellow croaker fish in the hotel's rustic restaurant -- but staff denied the existence of the room where court documents say the murder occurred.

"There is no room 1605," a hotel receptionist who declined to be named told AFP. "I do not know what you are talking about."

Bo, the son of one of China's most revered revolutionary generals, met Heywood when he was mayor of the eastern port city of Dalian in the late 1990s.

Prosecutors told a court during his trial that businessmen had paid for foreign trips and transferred millions to his family in return for government support during the period.

An English teacher turned business consultant who was fond of linen suits, Heywood cultivated an aristocratic air reflecting his former attendance at the elite British boarding school Harrow.

He became close to Bo as well as his wife, a prominent lawyer, and guided their son Bo Guagua as he started studies at the 22,400 pounds ($35,000) a year Papplewick prep school in Britain, before going on to Harrow, Oxford and Harvard.

As his connections with Bo and Gu deepened, Heywood reportedly bought an expensive villa in Beijing, and a Jaguar sports car with the licence plate "007".

Bo's family, meanwhile, is said to have amassed property in France, and luxury apartments in Britain and the United States. Reports say Heywood helped invest millions from their fortune in foreign assets.

But as Gu became closer to Bo's right hand man in Chongqing, Wang Lijun -- a flamboyant martial-arts trained policeman from Inner Mongolia -- Heywood's relationship with her began to sour.

The two clashed over payments on a business deal, according to the official account of Gu's trial. In November of 2011, in the dingy room at the Lijing Holiday Hotel, Gu plied Heywood with alcohol, and poured a cyanide-based poison in his mouth, a Chinese court heard.

When Heywood's body was discovered, he was diagnosed as having suffered a heart attack before being quickly cremated.

But the scandal became public early last year after Bo fell out with Wang over the murder, punching him in the face so hard that "liquid dripped out of his ear", according to Wang's trial testimony, and sacking him from his post.

At his trial, Bo accused Wang of being in love with his wife, and said that Wang "slapped himself eight times" in front of him and Gu when his romantic feelings for the lawyer became known.

Shortly after, Wang appeared at the door of the US consulate in the neighbouring city of Chengdu, offering a raft of secrets to stunned diplomats.

A stand-off involving hundreds of police vehicles ensued before Wang was escorted to Beijing by a top Chinese security official, reportedly because he feared assassination by Bo.

As rumours of Bo's imminent arrest began to swirl, he remained defiant, telling reporters in Beijing in March that accusations against him were "sheer rubbish".

But a terse announcement by China's state news agency days later sealed his fate: Bo had been relieved of his post and faced an internal party investigation, bringing his political career to an abrupt end.

Even so, it took more than a year for his case to come to trial, as analysts say factions of the ruling party negotiated over his fate. He was finally charged with corruption and abuse of power, and tried over five days last month.

Gu and Wang were both convicted in carefully-orchestrated trials, which saw Gu handed a suspended death sentence -- usually commuted to life in prison -- for the murder of Heywood, and Wang 15 years in jail for his role in its cover-up.

Bo mounted a stunning defence at his trial, where both Gu and Wang testified, denying his guilt, and calling his wife "crazy."

But the court, which rules on Sunday, is almost certain to find Bo guilty, and the man who once seemed destined to become one of the most powerful in China is now expected to spend decades of his life under house arrest, or even behind bars.