thumb|A gun emplacement at Middle Head on Sydney Harbour, used in one of the scenes in the movie. In the scene an under cover police officer (Stone) was initiated into the bikie gang
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.