Karl is first seen at the place where the Thing's UFO was found. He is there together with Edvard and Juliette and he is introduced to Kate Lloyd. He is helping with examining of the frozen Thing on the base and he takes the sample of the Thing at the order of doctor Halvorson - the fact which led to awakening of the Thing after long years in the ice.
During the celebration party, he is asked by Colin if they will gain some extra money for finding the alien.
Once the original Thing is burned along with Henrik, he is seen checking the state of Olav who becomes very sick after exposure to Henrik's blood. He assists Halvorson during the autopsy of the remains of the Thing along with Kate and Adam.
Following the crash of the helicopter, Kate presents her theory about the abilities of the Thing to imitate living organisms to the rest of the station. The majority of people are sceptical, and Karl is no exception. They are proved wrong very soon (and Karl unfortunately fatally) when Juliette-Thing reveals itself and tries to assimilate Kate. Kate manages to escape but she is followed by the creature. She runs past Karl and tries to warn him, but he is too slow to react as is horrified by the appearance of the Thing. He is attacked and mauled by Juliette-Thing then when Lars appears with the flamethrower to burn the imitation, he is apparently killed.
The Karl's dead body is later burned with the remains of Juliette-Thing in the snow for good.
- He has a resemblance to Fuchs.
- In a deleted scene, after Jonas extinguished the fire they go back to check on his dead body, but he is gone and Lars follows his blood trail. He then sees Karl get up from behind a desk. The wound he sustained is gone. Seeing the others, he lets out an inhuman roar before being incinerated, revealed to be Karl-Thing.
- He seems to be the physician of the station as he is treating Olav after his traumatic experience and is assisting Halvorson during the autopsy of Alien Thing, he was also aware of the medical conditions of Henrik.