A man wakes up on a beach. He has no recollection of who he is. He sets off in search of his past. His only clues are the number 13 tattooed on his collarbone and the key to a safety-deposit box in one of New York's most prestigious banks.
The passport he finds in the safe at the bank reveals his identity. His name is Steve Rowland and he's a captain in the United States Army. Moments after making this discovery, he's arrested by colonel Amos, director of the FBI's anti-terrorist department and accused of the murder of William Sheridan, the 43rd president of the United States.
Wanted by all the cops in New York State and hunted down by The Mongoose, the amnesiac seems doomed to a choice of death or prison. But XIII hasn't counted on the unexpected assistance of Major Jones, a young female soldier who helps him flee through the city of New York. During their escape, this foxy lady reveals to XIII that he's a secret agent working for General Carrington. Carrington is a nonconformist officer who is conducting a counter-inquiry into the presidential assassination but he was arrested and confined in an isolated military base in the Appalachian Mountains. When XIII realizes that general Carrington is the only one who can shed light on his past, he sets off to find him with Jones.