 In this episode, after the Mysterons threaten to assassinate a French intelligence agent, Captains Scarlet and Blue and Destiny and Symphony Angels go undercover to protect the target.The Mysterons (voiced by Donald Gray) warn Spectrum that they intend to assassinate André Verdain, a French fashion designer who is secretly Controller of the European Area Intelligence Service.Colonel White (voiced by Donald Gray) believes that they will make their attempt at Verdain's upcoming fashion show in Monte Carlo, and assigns a team of four – Captains Scarlet and Blue and Destiny and Symphony Angels (voiced by Francis Matthews, Ed Bishop, Liz Morgan and Janna Hill) – to protect him.