When Lucas, an agent investigating something subversive, gets off his train at the wrong station he is murdered. Has the crime got anything to do with a mole at the admiralty, a train ticket and a fiendish plot to kill the Prime Minister? This episode's guest stars include Drewe Henley, who also played Red Leader in Star Wars: Episode IV.
Elenco: Patrick Macnee , Honor Blackman , Diana Rigg , Linda Thorson , Ian Hendry .