Stone on AllMovie

An undercover cop named Stone (Ken Shorter) infiltrates an outlaw biker gang called the Grave Diggers, only to discover that he has more in common with the two-wheeled warriors than he previously though after a professional assassin attempts to set them up for a big fall. A prominent environmental activist has just been assassinated, and the police suspect that the Grave Diggers are withholding crucial information relating to the killing. Realizing that the Grave Diggers will never speak to regular policemen, the cops recruit Stone to ride with the gang and find out what they know. Accepted into the fold after saving the life of a grateful Grave Digger, Stone begins to respect the Undertaker (Sandy Harbutt) and his crew due to the fact that they operate by their own unique code of ethics. Later, as the Grave Diggers prepare to strike back against a rival motorcycle club, Stone suspects a set-up and attempts to convince them not to fall for it. Unfortunately for everyone involved, Stone was correct. When the violence finally erupts, no one is safe from the bloodshed that threatens to destroy the Grave Diggers, and consume Stone in the process.