Scott James (Chuck Norris) enlists an old friend (Lee Van Cleef) to avenge the death of his girlfriend at the hands of a deadly band of ninja assassins. He discovers the Octagon a sinister training centre for terrorism funded by international extremists who are covertly sending out ninja killers to cause worldwide mayhem. For Scott James there is no choice: he must face the truth of his childhood nightmares and face the Octagon and its killing machine.