A man washes ashore near an old couple's house, barely alive. When he comes to he has forgotten everything, including his name. The only clues to his identity: a key sewn into his clothes, a bullet wound to the head and the number XIII tattooed on his shoulder. A meagre start to reconstruct one's self. The central character in XIII is an amnesiac on the run, caught in the crossfire as he tries to understand his true identity while attempting to make sense of the various conspiracies swirling around him.