Attack of the Alligators!

"Attack of the Alligators!" is the 23rd episode of the British Supermarionation television series Thunderbirds. One of the last episodes of the first season, it was first broadcast on ATV Midlands on 10 March 1966, was written by Alan Pattillo and directed by David Lane. In this episode, alligators grow to a huge size when their habitat is contaminated by an enlarging chemical. The creatures proceed to threaten innocent people trapped inside a house, stirring International Rescue into action.

"Attack of the Alligators!" is often viewed as the most memorable episode of Thunderbirds for its incorporation of footage featuring actual crocodiles. This episode marks the first occasion when live animals appeared in a Supermarionation production. However, the episode proved to be a technical challenge to complete, and a representative of the Royal Society for the Prevention of Cruelty to Animals (RSPCA) supervised the recording to ensure no abuse of the creatures.

Plot
A businessman called Blackmer visits the reclusive Dr Orchard, a scientist who lives in a remote house on the Ambro River in South America. From the local plant sidonicus americanus, Orchard has developed a food additive called "Theramine" which, if fed to animals, causes them to exceed their original size. Enlargement of animal stock around the world would offer a simple solution to famine and present other financial advantages. Blackmer's boatman, Culp, has been eavesdropping on the meeting. When a storm forces Blackmer to stay at Orchard's house for the night, Culp resolves to abscond with the theramine and become rich. He waits until the other occupants are asleep and steals the keys to Orchard's laboratory from the housekeeper, Mrs Files. While filling a vial with a quantity of theramine, Culp accidentally knocks the rest of the supply into a sink and the chemical drains into the Ambro River.

When Blackmer and Culp leave Orchard the next morning, their boat is ravaged by an alligator, now enlarged due to the contamination. Orchard's assistant, Hector McGill, manages to rescue Blackmer, but Culp is apparently killed and the house is quickly surrounded by three giant alligators, which proceed to attack the building with Orchard, McGill, Blackmer and Mrs Files trapped inside. On the advice of Mrs Files, McGill contacts International Rescue and John relays the incredible details to Tracy Island. Jeff orders the launches of Thunderbirds 1 and 2. Arriving at the scene, Scott wards the reptiles off with his hoverjet missiles and enters Orchard's house through the laboratory window. Eventually the alligators cause so much damage that the laboratory caves in, forcing the Scott and the others to escape to the lounge. The group is confronted by none other than Culp, who has survived the alligator attack and holds them all at gunpoint.

Virgil arrives in Thunderbird 2 and repels the alligators away from the house with the vertical jets. Alan and Gordon man tranquilliser guns and subdue two of the creatures. When the third returns to the house, Alan leaves Thunderbird 2 on a hoverjet to lure the alligator off. Although Alan fails to notice a tree in his path and falls from his hoverjet, Gordon saves his brother by neutralising the last alligator. Culp threatens to pour the whole theramine vial into the Ambro River if he is not granted passage upstream. Launching Thunderbird 4, Gordon discovers a fourth, even larger alligator which attacks the boat and devours Culp. Virgil kills the final beast with a missile fired from Thunderbird 2. Despite fears that the vial has been smashed, Gordon retrieves it intact. Back on Tracy Island, Jeff announces that Orchard and Blackmer are putting international restrictions on theramine. Tin-Tin has been away from the island on a shopping trip and tells Alan that she has purchased a present for his upcoming birthday—which is revealed to be a pygmy alligator.

Production
Inspiration for this episode came from H. G. Wells' 1904 novel The Food of the Gods and How It Came to Earth, in which animal resizing is a significant theme, and the 1927 horror film The Cat and the Canary and its 1939 remake,  which concern stalker figures and a "haunted house" premise. Although script editor Alan Pattillo had wanted to direct as well as write the episode, the director role passed to David Lane. The episode underwent filming between October and November 1965, overrunning its month-long shooting schedule and forcing the production personnel to work well into the night on more than one occasion to finish the recording. A shot of a stormy sky seen in the episode's opening sequence is stock footage taken from the titles of the ITC television series The Prisoner.

Although co-creator and producer Gerry Anderson originally intended to shoot with real alligators, AP Films ultimately requisitioned juvenile crocodiles from a private zoo to appear as the giant alligators on the scale model sets. The crocodiles measured three feet (0.9 m) in length with the exception of one five-foot (1.5 m) specimen, which proved to be too aggressive to be removed from its container. Production members kept the on-set water tanks heated at an appropriate temperature and used electric shocks to produce movement from the crocodiles. The frequent appearance of the animals in both puppet and scale model shots resulted in a closer-than-usual collaboration between the puppet and special effects departments.

Objecting on the grounds of animal welfare, director of visual effects Brian Johnson, along with others, refused to participate in the production. While camera operator Alan Perry has no memory of ill treatment of the crocodiles, series supervising director Desmond Saunders recalls that more than one died of pneumonia after being left in an unheated water tank overnight. David Elliott, although occupied with directing another Thunderbirds episode at the time, remembers an incident in which one crocodile dislocated a limb after receiving an unexpected jolt from the electric shocker. Of the production, Saunders states, "It was scandalous. It was one of the great episodes. Nevertheless there was a price to be paid for it."

Disagreements on the subject of alleged mistreatment led to notification of the Royal Society for the Prevention of Cruelty to Animals (RSPCA). Initial tests with electric shocking had been unproductive, necessitating an increase in voltage to coax movement out of the crocodiles, as Anderson recalls: "[special effects director] Derek Meddings explained that his team were laying the crocodiles down and they weren't doing anything. They were just lying there. The RSPCA man said, well, they would, because of the warmth of the lamps. So Derek said, 'We've been giving them a touch with an electrode just to make them move.' The guy asked what voltage they were using and Derek said it was about 20 volts, and the guy said, 'Oh, they've got terribly thick skins, you know. If you want them to move, you'll have to pump it up to 60.'"

Filming with the crocodiles often proved to be hazardous. During a publicity shoot for "Attack of the Alligators!", one attacked the Lady Penelope puppet while it was positioned for a shot with two of the creatures and devoured one of the legs. While filming a scene in which one of the alligators pursues a boat, Meddings guided the animal forward on a harness when it was found that it had slipped loose and was swimming free inside the tank, forcing Meddings to jump quickly to safety. Puppeteer Christine Glanville has stated that the shoot must have been an unpleasant experience for the episode's "guest stars", once commenting, "The crocodiles must have had an awful time of it, lying in the studio tank, which was filled with all sorts of dirty paint water, oil and soapy water to make it look swampy."

Reception
"Attack of the Alligators!" remains a popular episode of Thunderbirds. Co-creator Sylvia Anderson cites it as her favourite episode, while critic Stephen La Rivière notes its plot as one of the most unusual in the series. Lew Grade, chief of the ITC which distributed Thunderbirds, expressed his delight with the filming when he visited the AP Films Studios during a recording session.

Since "Attack of the Alligators!" and a later episode, "The Cham-Cham", exceeded their budgets, the writing staff re-scripted the final instalment of Series One of Thunderbirds into a clip show, "Security Hazard". This episode makes extensive use of flashback footage to earlier episodes, which reduced costs.

Thunderbirds scriptwriter Dennis Spooner adapted the premise of "Attack of the Alligators!" for an episode of the The New Avengers in 1976. The episode "Gnaws" features a giant rat, grown to a monstrous size from the contamination of a water source due to a lethal chemical, which proceeds to attack humans.