In the early hours of October 31, 1993, River Phoenix left his friend Johnny Depp's exclusive Los Angeles nightclub the Viper Room and started convulsing. After a number of seizures, he was officially pronounced dead by paramedics at 1.51am. With the aid of dramatic reconstruction, the post-mortem report and interviews with close friends, forensic pathologist Richard Shepherd goes back over the last few weeks of the 23-year-old actor's life to try to unravel what happened on that fateful night