"Attack of the Alligators!" is an episode of Thunderbirds, a British Supermarionation television series created by Gerry and Sylvia Anderson and filmed by their production company AP Films (APF) for ITC Entertainment. Written by Alan Pattillo and directed by David Lane, it was first broadcast on 10 March 1966 on ATV Midlands as the 23rd episode of Series One. It is the 24th episode in the official running order. Set in the 2060s, the series follows the exploits of International Rescue, an organisation that uses technologically advanced rescue vehicles to save human life. The main characters are ex-astronaut Jeff Tracy, founder of International Rescue, and his five adult sons, who pilot the organisation's main vehicles: the Thunderbird machines. The plot of "Attack of the Alligators!" sees a group of alligators grow to enormous size after their swamp is contaminated by a new food additive. When the reptiles lay siege to a house, International Rescue is called in to save the trapped occupants. Combining science-fiction and haunted house themes, with a plot deliberately written to be "nightmarish", "Attack of the Alligators!" was filmed at APF Studios in Slough in late 1965. It was the first APF production to use live animals, the re-sized alligators being played by juvenile crocodiles. Filming of the episode was controversial as the crew resorted to using electric shocks to coax movement out of the animals. Concern for the crocodiles' welfare prompted an investigation by the Royal Society for the Prevention of Cruelty to Animals (RSPCA), which ultimately took no action against APF. "Attack of the Alligators!" remains a favourite with Thunderbirds fans and commentators and is generally regarded as one of the series' best episodes. Along with "The Cham-Cham", the next episode to enter production, it went over-budget, causing the final instalment of Thunderbirds Series One ("Security Hazard") to be re-written as a clip show to lower costs. In 1976, "Attack of the Alligators!" inspired an episode of The New Avengers titled "Gnaws", written by ex-Thunderbirds writer Dennis Spooner. Plot A businessman, Blackmer, visits the reclusive Dr Orchard, a scientist who lives in a dilapidated house on the Ambro River. From the local plant Sidonicus americanus, Orchard has developed a food additive called "theramine" that increases the size of animals. Enlargement of animal stock presents a simple solution to world famine as well as other economic advantages. Blackmer's boatman, Culp, has been eavesdropping on the meeting.