In June 1586, Tichborne agreed to take part in the Babington Plot to murder Queen Elizabeth and replace her with the Catholic Mary, Queen of Scots, who was next in line to the throne. The plot was foiled by Sir Francis Walsingham, Elizabeth's spymaster, using double agents, most notably Robert Poley who was later witness to the murder of Christopher Marlowe, and though most of the conspirators fled, Tichborne had an injured leg and was forced to remain in London. On 14 August he was arrested and he was later tried and sentenced to death in Westminster Hall.