"Relax? With three giant alligators knocking the house down?"
— Dr. Orchard

"Attack of the Alligators!" is the twenty-third episode of Thunderbirds Season 1, first broadcast on March 10th, 1966. It was the 24th episode produced.

In South America, a scientist has developed a unique growth substance. But his altruistic design for it goes dangerously awry when a small sample gets into the local water supply...causing three alligators in the nearby river to grow to giant sizes! The scientist and his household barricade themselves inside, whilst the enraged aquatic creatures outside repeatedly attempt to smash their way through...


A ramshackle motor boat, named Maria, slowly chugs its way along the Ambro River, in the jungles of South America. Aboard is a businessman called Blackmer; his destination is a remote house belonging to the reclusive scientist Dr. Orchard, who greets his visitor as Maria arrives at his dock. From the local plant Sidonicus americanus, Orchard tells his visitor, he has developed a food additive called "Theramine" which, if fed to animals, causes them to grow - considerably beyond their natural size. Such enlargement of animal stock around the world, he believes, would offer a simple solution to famine, along with other financial advantages. Unknown to either of them, however, someone else is furtively eavesdropping on their conversation...

That "someone" is Blackmer's boatman, Culp. When a storm forces Orchard's two visitors to stay at the river house for the night, Culp resolves to abscond with the Theramine and use it to become rich. He waits until the other occupants are asleep...then quietly lifts the keys to Orchard's laboratory from the housekeeper, Mrs. Files, and steals down to the basement laboratory. While filling a vial with a quantity of Theramine, Culp accidentally knocks the rest into a sink, and the chemical drains into the river...

The next morning, Blackmer and Culp board Maria and depart Orchard's house. But their journey downriver ends in disaster, when Maria is smashed into kindling by an enraged alligator - one now expanded to an extraordinary size! Orchard's assistant, Hector McGill, manages to rescue Blackmer, but Culp has vanished, and is presumed dead. Three giant alligators quickly surround the river house and proceed to attack it - with Orchard, McGill, Blackmer and Mrs. Files now trapped inside.

Thunderbirds Attack of the Alligators

Oversized alligators attacking the house where Blackmer, Mrs. Files, Dr Orchard, and his assistant, Hector McGill, are trapped.

On Mrs. Files' advice, McGill contacts International Rescue. Up on Thunderbird 5, John is incredulous - "Giant alligators!?" - even as he relays the incredible details to Tracy Island. Jeff orders the launch of Thunderbird 1 and Thunderbird 2 (carrying Pod 4)...

Arriving at the danger zone, Scott takes to his hoverjet and uses its missiles to ward off the alligators from the area around the river house, long enough to allow him to enter through the laboratory window. By now, the alligators have caused so much damage that the laboratory eventually caves in, forcing Scott and the others to escape to the lounge...where they're confronted by none other than a very-much-alive Culp, who shoots Scott's gun from his hand and proceeds to hold them all at gunpoint...

Virgil arrives in Thunderbird 2, and uses its vertical thrusters to repel the alligators away from the house. Alan and Gordon, manning tranquilliser guns, subdue two of them. When the third alligator returns to the river house - and against his brothers' orders - Alan leaves TB2 on his own hoverjet, attempting to lure it away, successfully at first. But then, failing to see a tree in his path, Alan falls and then slumps unconscious. Gordon saves his brother, by neutralising the 'gator. Meanwhile, Culp is threatening to pour the entire vial of Theramine into the river, if he is not granted safe passage upstream. Gordon launches Thunderbird 4 into the river, and discovers a fourth, even larger, alligator - which attacks Culp's escape-boat and kills him before being itself killed by Virgil, with a missile from TB2. Gordon then suits up in diving gear and takes to the river, searching for the now-missing vial of Theramine. Despite fears that it may been smashed, Gordon retrieves it, intact...

Back on Tracy Island, Jeff announces that Orchard and Blackmer are putting international restrictions on Theramine. And Tin-Tin, who's been away from the island on a shopping trip, tells Alan that she has purchased a special present for his upcoming birthday. It is revealed to be...a pygmy alligator!

Regular Voice CastEdit

Guest Voice CastEdit

International Rescue Equipment UsedEdit

Non-International Rescue Equipment UsedEdit


  • This episode is a favourite among fans for its use of real alligators (or rather, real crocodiles). Some members of the production team had the RSPCA called in during filming, though the RSPCA representative ended up giving the crewmembers advice on the voltage that would be needed to make the alligators move. Nevertheless, visual effects director Brian Johncock declined to play any part in the making of this episode, as he thought that the use of electricity to encourage the crocodiles to move when needed was unnecessarily cruel.
    • One of the RSPCA members even became part of the production crew after he stated that Thunderbirds was his favourite television series.
  • The stock footage of the thunder sky was later used for the opening titles of ITC series The Prisoner.

Thunder Sky

  • Although he did not write this episode, it is possible Dennis Spooner may have reused the idea of an enlargement drug being washed down a sink causing animals to grow for Gnaws, one of his episodes for The New Avengers. In that, a giant rat was substituted for the giant alligator.
  • This episode was filmed late in 1965.


  • The camera and its operator can be seen reflecting off the window as Mrs. Files watches Blackmer and Culp arrive at the beginning.
Goof 1 ep24
  • Jeff suggests that Pod 6 should be used, but if you look closely as Thunderbird 2 releases the pod, you can see that Pod 4 has been selected.
  • When Culp is walking from his boat to the outside lab window, some dialogue from Dr. Orchard describing the theramine process can be heard in the background. In the next scene, the same process is described with the very same dialogue soundtrack.
  • When one of the alligators attacks Blackmer and Culp, the first splashing results in their clothes getting wet. However, on the second splashing, their clothes are dry.
  • When the third giant alligator turns over after being shot at by Gordon, a bit of water can be seen jumping into the air at the very end of the shot, indicating that the shot was played backwards in order to achieve the effect that the crew wanted.


Main article: Attack of the Alligators!/Transcript

Alternate VersionsEdit

Thunderbirds (Fox Kids Series)Edit

Main article: Attack of the Alligators (Fox Kids Series)

Turbocharged ThunderbirdsEdit

Main article: Attack of the Alligators! (TCTB)

Foreign TitlesEdit

Attack of the Alligators (Italian)

Italian 8mm home movie

  • French: L'attaque des alligators
  • German: Angriff der Alligatoren
  • Spanish: El Ataque de los Caimanes
  • Italian: La battaglia degli alligatori (8mm); L'attacco degli alligatori
  • Dutch: De krokodillen vallen aan (TV); Monsterlijke dreiging (VHS); Aanval van de alligators! (VHS, DVD)
  • Japanese: 大ワニの襲撃

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