Frank Wolff is a fictional character from The Adventures of Tintin series of classic comic books drawn and written by Hergé (1907-1983). Wolff appears in Destination Moon (1950-52) and Explorers on the Moon (1952-53).
He is a meek and amiable scientist who assists Tintin's friend Professor Calculus before and during the Syldavian expedition to the moon. However, Wolff is ultimately exposed as a spy who was coerced into helping an unnamed foreign power to hijack the moon rockets he had helped to build.
The character of Frank Wolff is believed to have been based on the spy Klaus Fuchs, although Fuchs, a committed Communist, betrayed secrets for reasons of ideology rather than blackmail (the name interaction is also noted in the fact that in German, "Fuchs" means "Fox").
Although not named, the individual who offered the financial help to Wolff may have been Miller, the leader of the attempts to hijack the Syldavian rockets and who can be seen listening to the radio transmissions between Earth and the moon rocket in Explorers on the Moon [See below regarding reasons for this assumption].
At heart a decent man, Wolff fled to Europe and put his past behind him. He eventually found employment on the Syldavian moon rocket programme at the Atomic Research Centre at Sbrodj ["Sprodj" in the English-language edition], an area within the fictional Balkan kingdom, and became Calculus' dependable right-hand. He was a key figure in the development of the moon mission, being one of only three people to know the combination of the safe where the plans for the rockets were kept.
When Captain Haddock and Tintin arrived at the Centre, Wolff took them on a guided tour of the premises. As a scientist himself, he got a bit over-technical as to the workings of atomic batteries which went over Haddock's head, even if he tried not to show it.
At the time, he and Calculus were working on an experimental rocket named X-FLR6. It was to orbit the moon before returning to Earth with pictures of the other side, unseen from Earth. Wolff took microfilms of the plans and passed them to the spies via the Centre's air conditioning system. He was almost caught in the act by Captain Haddock whom he was forced to knock unconscious.
X-FLR6 was launched and, thanks to the plans provided by Wolff and passed on by Miller, the unnamed foreign power employing the spymasters was able to intercept it during its journey back to Earth. However, on Tintin's recommendation, Calculus had installed an auto-destruct mechanism aboard the rocket thus enabling it to be exploded at high altitude and thwarting the spies' plans.
Wolff incurred the wrath of Captain Haddock by refusing to allow him to take any alcohol or tobacco into the rocket — although the captain managed to smuggle some bottles of his favorite libation on board anyway.
Wolff continued his work on the construction of the rocket and the suits needed for exploring the surface of the moon. Eventually he set off for the moon along with Tintin, Haddock, Calculus and Snowy. Also along for the ride were the comic-relief lookalike detectives Thompson and Thomson who had taken it upon themselves to watch over the rocket before its launch, which they thought was scheduled for 1:34 p.m. rather than 1:34 a.m.
Wolff assisted Calculus in the handling of the rocket — turning it around as it approached the moon and positioning it to land in the centre of the Hipparchus moon crater.
Once on the moon, he assisted the "journalist" out of the crates in which he had been smuggled aboard. His actual identity was Colonel Boris, aka Jorgen, an enemy Tintin had met in King Ottokar's Sceptre. Jorgen revealed that his real mission was to take the rocket back to the foreign power which was employing them both. It was apparently this bitter realisation which led Wolff to mishandle the controls of the rocket's ladder and airlock soon after the others had set foot on the moon. Tintin himself had noticed how on edge Wolff had been for some time, in contrast to the amiable mood he was in when they first met.
Wolff and Calculus then set about performing various experiments on the lunar surface and observing the stars from there. He also went exploring in the lunar tank with Tintin and Haddock.
Later, when the other members of the crew had departed in the tank-like vehicle on an expedition that was to last two Earth days, Jorgen knocked Tintin and Snowy out and then pushed Wolff into starting the rocket in order to take it back to Earth, in spite of the scientist's objections to leaving the others behind. Just as it was taking off, the rocket crashed back on to the moon. Jorgen accused Wolff of sabotage and threatened to kill him. Tintin intervened and took them both prisoner. It was he who had grounded the rocket.
On the return trip, Wolff and Jorgen managed to free themselves. Jorgen had promised Wolff to let the others live, but he then went back on his word and announced that he was going to kill them anyway. Horrified, Wolff jostled Jorgen's gun arm and, in the struggle that followed, Jorgen's gun went off, killing him.
Wolff was allowed to rejoin the others, though Haddock still suspected him of possible betrayal. Jorgen's body was cast into space — it was too dangerous to keep a dead body in the rocket with a diminishing air supply.
Wolff was still overcome with guilt over the way he had betrayed his companions. While the others were asleep to save oxygen, Wolff slipped away and let himself out of the airlock, thus leaving them enough air to get back to Earth. Even the cynical Haddock who had, until the last moment, still suspected Wolff of treachery, was moved by his selfless act.