A Force Of One [DVD] [1979]

A team of undercover narcotics agents is conducting an investigation when things mysteriously begin to go haywire. One by one, the squad members are eliminated by an assassin. To help identify the karate killer, the police enlist the aid of karate champion, Matt Logan (Chuck Norris). Initially disinterested, he is galvanized into action when his adopted son is killed by the villains. He eventually tracks down the serial killer (Bill Wallace), a traitor within the police force, and brings his reign of terror to an end in a no holds barred climactic karate battle between the two men.