When several members of the GraveDiggers outlaw motorcycle club are murdered, Sydney detective Stone (Ken Shorter) is sent to investigate. Led by the Undertaker (Sandy Harbutt), a Vietnam war veteran, the GraveDiggers allow Stone to pose as a gang member. Leaving behind society girlfriend Amanda (Helen Morse), Stone begins to identify with the Undertaker and his comrades Hooks (Roger Ward), Toad (Hugh Keays-Byrne), Dr Death (Vincent Gil), Captain Midnight (Bindi Williams), Septic (Dewey Hungerford) and Vanessa (Rebecca Gilling), the Undertaker’s girlfriend. Amid violent confrontations with the Black Hawks, a rival gang the GraveDiggers hold responsible, Stone uncovers a political conspiracy behind the killings. When the truth is revealed, Stone must choose between his job and his loyalty to the GraveDiggers.