Adrian, also known as The Biting Snowman, is the main antagonist of one of the Austrian "Tom Turbo"-books. His Alter Ego is also adapted into a TV-episode for Christmas, where he is Dr. Gruselglatz in disguise.
At their hotel in the mountains, Tom and the kids notice several people diappearing, while snowmen with their hats appear. This fits the legend of a snowman that can turn people into snowmen by biting them. After a woman searches for her boyfriend, who was also transformed, she recieves a letter in which someone tells her not to go the police, signed with Emilio Eisig. She later disappears as well. After being almost completely frozen, Tom is picked on by a boy named Adrian. Tom later meets Adrian again, who apologizes for being mean earlier, but still makes Tom suspicious.
After Karo got apparantely turned into a snowman, too, Tom investigates further and meets an old hermit called Cornelius, who gives him the location of the mountain he wants to climb for investigations, but refuses to help him otherwise. Meanwhile, Karo realizes that she's inside the snowman, which is a machine that can trap people in its stomach while building a snowman and placing the person's hat on it, making everyone think that the person got turned into a snowman instead of kidnapped. Tom Turbo manages to find tthe secret hideout where all the kidnapped people are. The Biting Snowman attacks Tom to crush him with its weight, but Tom gets out of the way. It is then revealed that the robot is piloted by Adrian. Adrian worked in the hotel as a chef, but then he was fired by his boss for new reason but her being in a bad mood. This is why he kidnaps people to ruin the hotel. Before he can trap everyone in his hideout, Cornelius, who did follow Tom after all, pulls a sack over him to save the others. Adrian presumably ended in prison afterwards.
The story about the Biting Snowman was later adapted into a Christmas special for the TV-show (which has a completely different continuity than the books, as it doesn't feature Karo or Klaro and has Tom work as a private detective instead), however its plot differed greatly from the book, the titular Snowman being the only thing they had in common, and Adrian was not featured. Instead the snowman turned out to be Dr. Gruselglatz, who served as a member of a conspiracy of Tom Turbo's greatest enemies in the TV show (Fritz Fantom, Freda Fantom, Dr. Gruselglatz, Rudi Rat and Rosso Robot). Dr. Gruselglatz was supposed to scare people away from a mountain as this was the location of Fritz Fantom's hideout.
Die heiße Spur