Steed impersonates Riordan, a forger soon to be released from prison, and gains the trust of gang-leader Hooper. Things seem to be going well until Hooper's second-in-command, known as the Cardinal, announces that Riordan's girlfriend is outside waiting to see him.

How has a research centre developing radiation-proof material managed to irradiate one of its scientists? Once more, Steed submits himself to scientific testing.

A man is murdered whilst being interviewed on live television. one-Ten is sure that it is the work of the ruthless assassin Mr Teddy Bear, and he asks Cathy Gale to trap the man - by arranging for him to murder Steed.