Hapka was one of the Cleaners who accompanied Selene to a abandoned fortress high up in a mountainous valley where William Corvinus's prison was located. Of the five-man team that accompanied Selene into the dungeon, he was the one of the first two to be mauled by William Corvinus, infecting him with Lycanthropy.
Hapka initially died from shock trauma and blood loss, but within a few minutes, he began to revive and Change into a first-generation Werewolf under the full moon. After Selene finished off Samuel and Greenway after they started to Change, Hapka, (fully Changed), along with Parks, (also fully Changed), and Levin, (partially Changed), all three converged on Selene, putting her in a position where she could not attack one without leaving herself open to attack from the other two. However, a feral Levin attacked Selene first, and Selene defended herself with her Silver hunting Knive into his shoulder, just as a revived Michael Corvin entered the fight.
It is unknown if Hapka was the Werewolf killed by Michael Corvin by putting a arm right through his torso, (in the novelization, it was by ripping out his spine), or the Werewolf killed by Selene with Levin's Uzi automatic, before finishing Levin off himself.
- "Although a veteran in the Cleaner corps, with six years of experience in the field, [Karl Hapka] found himself unusually on edge." ~Evolution novelization, chapter 21