"Big Ben Strikes Again" is the third episode of Captain Scarlet and the Mysterons, a British Supermarionation television series created by Gerry and Sylvia Anderson. Written by Tony Barwick and directed by Brian Burgess, it was first broadcast on 13 October 1967 on ATV Midlands. In this episode, the Mysterons attempt to destroy London by hijacking a transporter truck and turning its cargo – a nuclear device – into a time bomb. Spectrum's key to locating the device before it detonates lies in solving the mystery of the truck driver's claim that he heard Big Ben strike 13 at midnight.