With their investigation complete, Timmons's team submit their file to the Crown Prosecution Service, which charges Lugovoy and Kovtun with Litvinenko's murder.

A team of detectives led by Timmons's "best man," Brian Tarpey, arrives in Moscow to interview the prime suspects behind Litvinenko's murder.

Watched by the world, the Metropolitan Police follow the radioactive trail of polonium across London, leading them to their main suspects, Lugovoy and Kovtun.

November, 2006. Detective Inspector Brent Hyatt and Detective Sergeant Jim Dawson, are summoned to University College Hospital in London to interview a man named Alexander Litvinenko, a former Russian spy who claims to have been poisoned. Litvinenko's wife, Marina, tells the detectives that the doctors are sceptical of his story, though the Russian's deteriorating physical condition is clear for everyone to see. Over three agonising days, Hyatt and Dawson interview the dying Litvinenko, who provides a meticulous account of who he believes to have killed him, and also the man responsible for ordering his murder, none other than Vladimir Putin.

Explorative documentary following the investigation into Litvinenko's murder. Who were the people behind-the-scenes who dealt with a deadly radioactive poisoning on British soil?