"Special Assignment" is the tenth instalment of the Supermarionation television series Captain Scarlet and the Mysterons. It was first broadcast in the UK on December 1st 1967 on ATV Midlands, was written by Tony Barwick and directed by Robert Lynn. In this episode, Captain Scarlet appears to betray Spectrum after the Mysterons threaten to destroy North America.
Shortly after the Mysterons threaten to destroy the whole of North America, Captain Scarlet is dismissed from Spectrum for gambling on duty. Broke, and owing $5,000 to the Dice Club, a casino in Nevada located just outside the Nuclear City city limits, Captain Scarlet (now calling himself "just plain Paul Metcalfe") moves into an Arizona hotel. He is soon approached by Messrs. Steele and Kramer, two extortionists who have been killed and replaced with Mysteron likenesses to carry out their threat, and agrees to provide them with a Spectrum Pursuit Vehicle for "private use" if they rid him of his debt. The Steele and Kramer likenesses will use the vehicle to penetrate Nuclear City in Nevada. They will then detonate a nuclear device, creating a chain reaction powerful enough to obliterate the whole North American continent.
But Captain Blue, suspicious of Captain Scarlet's uncharacteristic gambling and the manner of his dismissal, has been tracing his friend to find out the truth behind events. When Captain Blue arrives at the desert ranch house where the details of the Mysteron plan are being revealed, "Mr. Metcalfe" shoots his friend to reassure the Mysteron agents that he is on their side. Captain Blue, however, is hit only with a sedative dart, and after regaining consciousness, he is informed by Colonel White that Captain Scarlet had been operating undercover to infiltrate the Mysteron plot. Captain Blue learns that Nuclear City is being targeted by means of a map left at the ranch. The Angels are launched from Cloudbase as Captain Scarlet and the Mysteron agents speed towards Nuclear City in a commandeered SPV. Driving, Captain Scarlet emits smoke from the vehicle to signal the Angels to attack it. Realising he and the Kramer likeness have been betrayed, the Steele likeness shoots Captain Scarlet, but the officer ejects from the SPV before it is hit and explodes. The Mysterons have failed.
Later, Captain Scarlet, Captain Blue, Colonel White, and Lieutenant Green, all outfitted in civilian clothes, all visit the Dice Club. Lieutenant Green has worked out a roulette wagering system, and asks for assistance with testing it, but Captain Scarlet chides him, "Leftenant! You know I never gamble!"
Several scripting changes were made between the original version of Tony Barwick's script and the final edit of the episode. At the earliest stage of development, the episode was to open with Captain Scarlet losing at the casino. Modifications to the script added a prelude depicting the deaths of Steele and Kramer, both of whom are killed in a vehicle accident, and their replacements with likenesses. For the completed episode, the death sequence is expanded with a garage mechanic, Mason, being murdered by Captain Black, reconstructed himself and then sabotaging the brakes of Steele's and Kramer's vehicle, which later loses control and flies over a cliff edge, killing the men. Although the Steele and Kramer likenesses are destroyed by the end of the episode, the fate of the Mason likeness is left unspecified.
As Captain Blue arrives at the ranch house, he is shown to be driving an unmarked car in a long-distance shot which changes to a Spectrum Saloon Car in a close-up shot. "Special Assignment" also marks one of the few occasions in the series in which Colonel White is shown to be away from Cloudbase, for a closing scene at the casino. The only other cases are his undercover departure in "White As Snow," attending the conference in "Spectrum Strikes Back" and piloting a Spectrum Jet with Captain Scarlet in "Flight to Atlantica." All the music in this episode is re-used from a track library of previously recorded pieces. Notable among the recycled music is the TVR-17 tune "White as Snow," which can originally be heard in the episode of the same name and features here during the opening sequence set at Mason's garage.
Critics Chris Drake and Graeme Bassett discuss the unusual nature of the plot of "Special Assignment," writing that it "contains more than one red herring" in the case of its characters.