Driving a car, Captain Black murders a filling station attendant called Mason by running him over. The Mysterons create a replica of Mason under their control. Later, con artists Steele and Kramer pull in to have their car's brakes serviced. Instead of topping up their brake fluid, the reconstructed Mason drains it. Back on the road, Steele and Kramer are unable to stop at a cliff edge and are killed when they crash onto the slope below. They are then replicated by the Mysterons, who transmit a message to Earth vowing to destroy the whole of North America. After meeting with Colonel White regarding a "special assignment" concerning the Mysterons' threat, Captain Scarlet visits a casino and, with uncharacteristic poor judgement, ends up losing $5,000 on roulette. When he is unable to pay his debt, the casino informs Spectrum and Scarlet is dismissed from the organisation. Broke, Scarlet moves into an Arizona hotel. He is soon approached by the reconstructions of Steele and Kramer, who offer to write off his debt in exchange for a Spectrum Pursuit Vehicle. Agreeing to this proposal, Scarlet learns that the men intend to use the SPV to attack Nuclear City, Nevada. Their aim is to detonate a nuclear device within the city, creating a chain reaction powerful enough to obliterate the North American continent. Concerned by Scarlet's recent behaviour, Captain Blue goes AWOL from Cloudbase to track down his friend. When Blue arrives at the desert ranch house where the Mysteron agents are unveiling their plan, Scarlet appears to shoot Blue dead to reassure his new allies that he is on their side. However, he has fired nothing more than a tranquiliser dart and Blue regains consciousness after the others leave to steal an SPV from a nearby garage. He is radioed by a furious White, who informs him that Scarlet has been working undercover to infiltrate and sabotage the Mysterons' plot. From a map left at the ranch house, Blue learns of the threat to Nuclear City and relays this information to White. The Angels are launched and intercept Scarlet and the Mysteron agents as they speed to Nuclear City in the SPV. Scarlet activates a smoke signal instructing the Angels to attack the vehicle. Realising that he and Kramer have been betrayed, Steele fatally shoots Scarlet, but the captain ejects before the SPV is destroyed, killing Steele and Kramer and saving Nuclear City. Later, the revived Scarlet is joined by Blue, White and Lieutenant Green for an off-duty night at the casino.
Production
For timing reasons, several script changes were made during production. As originally scripted, the episode began with the gambling incident that sees Scarlet dismissed from Spectrum. However, as the first cut of the episode was too short, this was changed by adding several new scenes. The first of these were Steele and Kramer's deaths in a car crash and their subsequent reconstruction by the Mysterons, followed by Colonel White addressing Cloudbase personnel after the Mysterons issue their threat. Later, as the episode was still under time, Captain Black's murder of Mason and the reconstructed Mason's sabotage of Steele and Kramer's car were also added. The script describes Nuclear City as housing all of North America's nuclear weapons and radioactive materials; however, this is not conveyed in the finished episode. The Mysteron threat as stated in the finished episode is truncated from the scripted version, in which the Mysterons specifically vow to destroy North America within seven days. The casino set incorporated props that had previously appeared as part of the Creighton-Ward Mansion dining room in Thunderbirds. The miniature roulette props were parts of a toy set produced by Merit Toys and had previously appeared in the Thunderbirds episode "The Duchess Assignment". The ranch house scale model was a modified version of the hunting lodge seen in "Spectrum Strikes Back". All music in "Special Assignment" is taken from earlier episodes. One of the recycled tracks is "White as Snow", which was originally composed for the episode of the same name and can be heard during the scene of Mason's murder. The music accompanying the closing scene was originally composed for the Thunderbirds episode "30 Minutes After Noon". Although the script states that Blue travels to the ranch house in a Spectrum Patrol Car, the model shot shows him driving an unmarked car. The fate of the Mysteron reconstruction of Mason is not shown. "Special Assignment" is one of only a few episodes of Captain Scarlet in which Colonel White is seen away Cloudbase. The only other episodes in which he is shown to leave the base are "White as Snow", "Spectrum Strikes Back" and "Flight to Atlantica".
Reception
Chris Drake and Graeme Bassett note the unusual nature of the plot, writing that it "contains more than one red herring". Andrew Pixley and Julie Rogers of Starburst magazine regard Black's murder of Mason, done by running the attendant over with his car, as one of the series' more violent moments, also noting that Black kills another filling station worker in "Manhunt", where Black activates a car lifter that crushes the attendant in question.
