Inspired by the true story of a fraudster and murderer who preyed on tourists travelling through Asia in the 1970s, The Serpent is the latest true crime drama being binged in lockdown.
Starring Tahar Rahim as killer Charles Sobhraj, and Jenna Coleman as his lover and accomplice Marie-Andree Leclerc, the eight-part drama is currently showing on BBC1 and BBC iPlayer.
"A hidden darkness on Asia's hippie trail – the twisting, real-life story of a murderer, thief and seductive master of disguise," is how the BBC bills it, and reviews have praised Rahim's performance as the "ice-cold" killer who became one of Interpol's most wanted men.
Here are the details behind the drama.
Who is Charles Sobhraj?
A French national who was born Hatchand Bhaonani Gurumukh Charles Sobhraj to an Indian father and Vietnamese mother in what was then known as Saigon (now Ho Chi Minh City), Sobhraj led a life of petty crime as a teenager which escalated to much darker deeds.
Evading authorities using false passports across Thailand, India and Nepal, on what was known as the hippie trail travellers' route, he would pose as a drug dealer or gem salesmen to impress and get to know tourists, before robbing them.
He was accused of the murders of several Western tourists, playing cat and mouse with the authorities for years – his ability to give police the slip and escape jail earned him his Serpent nickname, although he also became known as the Bikini Killer as the bodies of several female victims were found in swimwear.
In The Serpent, he is seen poisoning his victims, burning the bodies of some, and leaving others to drown.
Sobhraj was eventually jailed in India in 1976. Ten years later, as his sentence was due to end, he escaped prison – knowing a Thai arrest warrant against him, which would almost certainly have led to the death penalty, was still valid. His escape and subsequent recapture meant his jail term in India was extended – and so he avoided execution in Thailand.
He was eventually released in 1997 and returned to France. Seemingly enjoying his notoriety, he gave media interviews about his life.
But in 2003, having travelled to Nepal once again, he was captured by police there and a murder inquiry was reopened. Some accounts suggest he was hoping to be caught once again, craving the attention. By 2004, he had been jailed again and now aged 76, he remains in prison.
What happened to Marie-Andree Leclerc?
Sobhraj had several followers, with his lover, Marie Andree Leclerc, the most prominent in The Serpent. Seemingly blinded by love and infatuation, she went along with his crimes.
Born in Quebec, Canada, she met Sobhraj while travelling in India.
As his accomplice, she was also jailed for her part in his crimes. However, in 1983 she was allowed to return to Canada as she was suffering from cancer. She died in 1984, aged 38.
Who is Herman Knippenberg?
In The Serpent, the story focuses on the investigations made by Dutch diplomat Herman Knippenberg, played by Billy Howle. Working at the Dutch embassy in Thailand, he started looking into Sobhraj's crimes after coming across the case of two Dutch travellers who had gone missing.
Eventually linking the disappearance to other deaths, he was able to build a case against Sobhraj with the help of one of the criminal's neighbours.
Ahead of the launch of the series, Howle told the Radio Times that he spoke to the real Mr Knippenberg while researching the role.
"It's a sort of moral outrage that drives this fastidious investigation that he takes upon himself," he said. "It's so unlikely, really, a person in this position doing the job that he was doing, for this to land on his desk, I think it is the moral outrage at the reality of this, the gravity of it, that drives him forward to want to stop it."
Sobhraj was convicted in Nepal over the deaths of Laurent Carriere, from Canada, and American Connie Bronzich, and in India of Frenchman Jean-Luc Solomon, however he is believed to have killed many more.
He has never been tried for crimes in Thailand. Other victims he is linked to include American Teresa Knowlton, Turk Vitali Hakim and his French girlfriend Charmayne Carrou, and Dutch students Henk Bintanja and Cornelia Hemker.
Some names have been changed in the drama out of respect for the victims and their families.
The series is dedicated "to all the young intrepids who set out with big dreams, but never made it home".
The Serpent is available to watch now on BBC iPlayer