Small-town lawman Sheriff Mark Kaminski, a dishonoured agent kicked out of the FBI for excessive brutality, agrees to lend an old friend a hand. But to infiltrate Luigi Patrovita's powerful Chicago mafia, the tough officer will need all the help he can get. As revenge fuels the suicide mission, Mark, now posing as the mysterious Joseph P. Brenner, must use every trick in the book to force his way through the crime organisation and tear it apart from the inside. For the sake of his friend, Mark takes the law into his own hands in this deadly unofficial assignment. However, how far can the intruder go without blowing his cover?