"Spectrum Strikes Back" is the ninth instalment of the Supermarionation television series Captain Scarlet and the Mysterons. It was first broadcast in the UK on November 24th, 1967 on ATV Midlands, was written by Tony Barwick and directed by Ken Turner.
The events in this instalment follow the "Operation Time" events. In it, Spectrum unveils two devices that it has developed to counter the Mysterons. However, a Mysteron agent leaves the conference delegates in mortal danger.
Colonel White, Captain Scarlet, and Captain Blue attend a top-secret conference held underground beneath a hunting lodge in an African game reserve. Also in attendance are the World President, General Peterson and lastly Dr Giadello, who has developed two anti-Mysteron devices based on the discoveries made when the Mysterons tried to assassinate General Tiempo. The "Mysteron Detector" can produce X-ray images to which Mysteron agents are impervious, making it possible to distinguish them from normal Earthmen, while the "Mysteron Gun" can fire an electron beam to kill Mysteron agents via their vulnerability to high electrical voltages. Both have an approximate range of fifty yards. However, Captain Indigo, a Spectrum officer who serves as the lodge waiter, has been murdered by Captain Black and reconstructed by the Mysterons. When the Mysteron detector accidentally reveals this, the Captain Indigo likeness sabotages the conference by locking the lodge in its descent setting. He then escapes in a car with the key to the control mechanism, leaving the delegates to be crushed by the building above them.
Armed with the Mysteron rifle, Captain Scarlet ascends in a lift. However, the lift ceases to operate when the lodge starts its descent, forcing Captain Scarlet to pursue the Captain Indigo likeness and attempt to retrieve the key. In the conference room, Captain Blue slows the lodge's descent by firing his gun into the ceiling at the point where the control mechanism is located. Captain Scarlet and a game warden prevent the Captain Indigo likeness from escaping the reserve. However, the Captain Indigo likeness is only wounded when the warden shoots him with his rifle, so Captain Scarlet uses the Mysteron rifle to destroy him. Rushing back to the lodge with the key, Captain Scarlet reverses the descent just before the five other delegates are killed. Later, the men agree that despite unexpected challenges, the Mysteron detector and rifle have both passed their unexpected field tests and proven their worth in the field.
"Spectrum Strikes Back" marks the second appearance of the World President, who was threatened with assassination in "The Mysterons". The puppet portraying Dr Giadello previously appears as Morton in "The Trap". In a four-hour studio session held on June 11th 1967, incidental music for both this episode and "Avalanche" was recorded by Barry Gray accompanied by an orchestra of 15 musicians. Released on CD, the suite for "Spectrum Strikes Back" totals eight minutes 33 seconds of music.