Transmitting to Earth, the
Mysterons warn Spectrum that they intend to assassinate André Verdain, the secret head of the European Area Intelligence Service. Publicly, Verdain is a celebrated
fashion designer, who runs the House of Verdain as a front for his spy network. Believing that Verdain's death would be disastrous for the Service,
Colonel White predicts that the Mysterons will make an attempt on the spymaster's life at an upcoming fashion show in
Monte Carlo, and assigns a team of four – Captains
Scarlet and
Blue and Destiny and Symphony Angels – to protect him. The agents go undercover as employees of Verdain, with Scarlet and Blue (going by their real names Paul Metcalfe and Adam Svenson) posing as a
public relations officer and a photographer, and Destiny and Symphony as fashion models. With the Paris airports closed due to fog, the agents are forced to fly to Monte Carlo direct. Unknown to Verdain and Spectrum, two of Verdain's models, Helga and Gabrielle, have been killed in a
monotrain derailment and replaced with Mysteron reconstructions. When Verdain takes his guests on a tour of Monte Carlo Bay in his
luxury yacht, Gabrielle starts a fire in the engine room that quickly consumes the vessel. All on board jump to safety only seconds before the yacht explodes. Despite Scarlet's warnings, Verdain refuses to cancel his press reception at a nearby hotel. A man resembling
Captain Black has been sighted in Europe and Verdain is sure that he will make an appearance at the event. During the pre-reception cocktail party, Gabrielle inadvertently reveals herself to be a Mysteron agent when she tells Scarlet that she flew in from Paris while it was fog-bound. Before Scarlet can challenge her, Black, who is waiting outside the hotel armed with a sniper rifle, shoots Verdain through an open window with a
tranquiliser dart. Gabrielle turns off the lights, and in the resulting confusion, Helga and Black bundle the unconscious Verdain into Black's car and speed away, bound for an unknown location. With the aid of a
homing drug that Scarlet put in Verdain's drink, the Spectrum team pursue the Mysteron agents by car,
SPV (obtained from a casino) and helicopter. Caught between the Spectrum forces and a police
roadblock, Black and Helga push Verdain out of their car and come to a halt. As Verdain regains consciousness, the Mysterons use their powers to teleport the car and its occupants away. Back at the hotel, Verdain thanks his protectors and presents Destiny and Symphony with splendid gowns courtesy of the House of Verdain. ==Regular voice cast==