Headed by Jeff, an industrialist and philanthropist, the Tracys run International Rescue, a search-and-rescue organisation operating on land and sea, in air and in space.
They carry out their missions using a range of technologically advanced vehicles and equipment headed by a fleet of five craft called the Thunderbird machines, piloted by Jeff's sons.
She helps her grandsons organise equipment that they need ("Sun Probe") and it is she who comes up with a solution for a rescue at the Bank of England when everyone else is out of ideas ("Vault of Death").
She also attends the filming of an edition of the Ned Cook Show in which the host thanks International Rescue for saving his life ("Terror in New York City").
In the remake, she has a different personality: she has taken over the role of head of the family following Jeff's disappearance, is tougher than the puppet version, and is a poor cook.
The son of a combine harvester driver on a Kansas wheat farm,[12][13] Jeff joined the United States Air Force and reached the rank of colonel.
[15] Each was named after one of the Project Mercury astronauts: Scott Carpenter, John Glenn, Virgil Grissom, Gordon Cooper and Alan Shepard.
"[19] In the remake Thunderbirds Are Go, Jeff vanished six years prior to the start of the series, for which The Hood is shown to be responsible ("Ring of Fire – Part 2").
Jeff finally appears in series 3, initially in recordings in the two-part episode "Signals", which reveals that he was last seen trying to stop The Hood stealing the Zero-X spacecraft.
After recovering The Hood's escape pod, Brains realises that the explosion was a shockwave created by the ship's faster-than-light drive, which propelled Jeff into deep space.
Working with former adversary The Mechanic, Brains builds the Zero-XL, a ship powered by the same engine as the Zero-X and capable of transporting all the Thunderbirds, allowing the Tracy brothers to follow the signal back to its source.
Educated at Yale and Oxford Universities, Scott was decorated for valour during his service with the United States Air Force before taking up his duties with International Rescue.
Of the five brothers, it is Scott who keeps a cool head, and who is quick-thinking when the situation calls for it – particularly when he is at the receiving end of a gun or when the security of International Rescue is compromised.
He is said to have "graduated from Wharton Academy" (the school that Alan attends at the start of the film) with "record grades" that remain unmatched by his brothers, "a fact he constantly reminds them of".
[10] He was the first of the brothers to be voice-cast; Barrett was so impressed with the puppet, whose looks were modelled on Adam Faith and Charlton Heston, that he immediately told Sylvia Anderson that he wanted to play the studious young astronaut with the boyish quiff.
[22] Over the course of the film, John is nearly killed by The Hood, who launches a missile at the space station to lure International Rescue away from Tracy Island.
Carolyn Percy of the Wales Arts Review writes that the original John was the least developed brother because he was disliked by Gerry Anderson.
She comments that with his "deeper characterisation", the remake version of John has "evolved into something of a breakout character", also noting that he is cast as a "slightly anti-social loner".
In "Terror in New York City", after he is seriously injured when Thunderbird 2 is mistakenly attacked by a warship, his first thoughts on waking are alarm at the fact that his craft is out of service when it could be needed at any moment.
[13] Shortly before International Rescue began operations, Gordon was involved in a hydrofoil speedboat crash when his vessel capsized at 400 knots (740 km/h; 460 mph).
According to Alex Pang's Thunderbirds: X-Ray Cross Sections, he is 18 years old and a recent graduate from Wharton Academy, the school that Alan attends in the film.
Carolyn Percy of the Wales Arts Review comments that whereas the 1960s character was one of the least developed brothers, this version of Gordon is clearly characterised as a "light-hearted joker".
[43] He studied at Colorado University, where his impetuousness led to trouble with the authorities over the launch (and subsequent crash) of an unsanctioned, self-built rocket.
His father took charge of the situation, steering the boy's interest toward more constructive ends, ultimately resulting in Alan's role as pilot of Thunderbird 3.
In "Atlantic Inferno", Alan pilots Thunderbird 1 and coordinates a rescue at sea while Scott remains on Tracy Island to fill in for Jeff, who is on holiday.
"[42] John Peel considers Alan to be evidence of the series' aptitude for strong characterisation, summing up his character as "love-struck and annoying", yet simultaneously "so human".
[45] Mark Radcliffe argues that the character is overshadowed by Scott and Virgil, who direct most of the rescue missions: "Poor Alan, despite having a rocket with much cooler fins than [Thunderbird 1], would then be dispatched to sort of see that everything was going OK.
In a negative film review for website The Spinning Image, Graeme Clark wrote that Corbet's Alan is the only brother to be given a distinct personality; by contrast, his siblings are "totally interchangeable".
[48] A retrospective on Den of Geek drew parallels between the new Alan and the protagonist of the Harry Potter novels and films, alluding to a reversal of the story concept "of a boy at home thrust into an adventurous world".
Alan's equipment includes an orbital conveyance platform which allows him to make close approaches to objects, such as the Sat-Mine in the episode "Space Race".