Upon learning that his days are numbered, a man and an old friend return to an old house that connects them by a dark secret. Along with three women and a mysterious old man, the group journeys into a horrifying abyss of debauchery and moral mayhem, leading to a fatal turn of events, during which the darkest human depths are revealed.

Cannibal is based on the true-crime story of Armin Meiwes, the "Rotenburg Cannibal" who posted an online ad searching for someone to volunteer to be mutilated and eaten. Unlikely as it may seem, someone actually replied. The film shows a fictional portrayal of the meeting between the cannibal and his victim/participant, their homosexual relationship, and the eventual mutilation and murder of said victim.

The trials and tribulations of a man diagnosed with colorectal cancer who refuses treatment and establishes a carnal fixation on the tumor that slowly siphons the life out of him.