Thunderbirds is the story of International Rescue, an elite, high-tech rescue squad headed up by multi-billionaire former astronaut Jeff Tracy, and headquartered at his private island somewhere in the south Pacific. Summoned by a radio set to any frequency, it is the last, best hope for those who cannot be rescued by any other means. This unit is staffed by Jeff's five sons: Scott, Virgil, John, Gordon and Alan, each of whom has his own specific vessel to man.

Scott, eldest of the Tracy sons, is pilot of Thunderbird One, a speedy silver rocket plane. He is first on the scene, and usually directs the action from his portable radio/computer unit, Mobile Control.

Virgil is the man at the controls of mighty Thunderbird Two, a heavy-duty cargo carrier whose interchangeable pods carry a variety of equipment, especially designed for different types of rescues.

John, space monitor and eye in the sky, mans Thunderbird Five, a communications satellite in geostationary orbit some 26,000 miles above the Earth. He is the first to hear cries for help, and is the touchstone between people in trouble, IR headquarters, and the rescue crew on the field.

He swaps places every other month with youngest brother, Alan, who pilots the sleek red rocket ship, Thunderbird Three. If there's a rescue in space, Thunderbird Three – and, in most cases, Alan – will quickly launch to respond.

Thunderbird Four – though tiny in comparison to the other ships – has a unique and important place in International Rescue's arsenal. It's a mini-submarine, carried to the danger zone by Thunderbird Two, and at the helm is aquanaut Gordon Tracy.

In the background – but of equal importance – are the brilliant engineer who made this all possible, Brains, and his assistant, the lovely Tin-Tin Kyrano. Security issues are often handled by International Rescue's London agent, English heiress and sometime model, Lady Penelope Creighton-Ward, part of IR's far-flung network of covert agents. She is aided and abetted by her butler/chauffeur, former top safecracker, Aloysius Parker. He drives her Ladyship's fabulously appointed pink Rolls Royce, FAB-1. Keeping the Tracy household running and the family well-fed are Jeff's Malaysian retainer, Kyrano, and Jeff's mother, known only as Grandma.

International Rescue, though primarily a rescue operation, often tangles with gangs, saboteurs, and thieves. The most persistent and dangerous of these is the Hood. Man of many faces, and half-brother to Kyrano, he exerts a strange, magical power over the retainer, gleaning information about the workings of the organization, and sometimes compelling the older man to perform small acts of sabotage so he can get closer to the secrets of the Thunderbirds themselves. So far, he's been thwarted at every turn by the agents and operatives of International Rescue.