End of the Great War. A captain of infantry, gravely wounded in combat, wakes up in a sanatorium, held captive by a man who claims to be his friend. Memories slowly return to him, mixed with those of another man, a soldier he led to the firing squad, and with flashing visions of a strange world, woven by spiders, where a mysterious merchant offers him a pact. But does this pact, which is supposed to help him find the woman he loves, address the captain or Eugène, the poet-soldier? Is this presence in the officer's head a threat? For Captain Sourpuss, the war is just beginning.