Is a mystery that has bewildered police and investigators for 50 years about to be solved? On 7 November 1974, the dead body of a children's nanny, Sandra Rivett, was discovered in a mail sack in the basement of a Belgravia townhouse. The chief suspect was the father of the children, an Eton-educated gambler called Richard John Bingham, the seventh earl of Lucan, who had disappeared. While most of Lord Lucan's friends and family insisted that he had taken his own life, no body has ever been found. The manhunt for Lucan has lasted decades. Thirty years after the murder, Hampshire builder Neil Berriman discovers he is Sandra Rivett's biological son. Along with his long-term collaborator, Glen Campbell, Neil revisits key moments and emotions in what has been a 17-year journey — starting at the night of the murder in Belgravia.