Two law-abiding citizens pose as ne'er-do-wells on choppers in this Sixties biker flick. The Hellcats are an outlaw motorcycle gang who spend their days swilling beer, looking for kicks and supporting their nomadic lifestyle by acting as drug mules for a small but powerful crime syndicate. An undercover cop was on the verge of infiltrating the Hellcats when the mobsters found him out and had him murdered; the late detective's fiancée Linda (Dee Duffy) meets his brother, former Army sergeant Monte (Ross Hagen), and they decide to pick up where he left off by posing as bikers and joining the gang to ferret out the killers. Monte and Linda soon discover that while the men do most of the carousing in the Hellcats, it's the biker mamas who do most of the work in transporting heroin, and Linda forms a dangerous alliance with Shelia (Sharyn Kinzie), the brains of the drug-running outfit to maintain her cover. Meanwhile, Monte finds Shelia is falling for his moody charm, despite Linda's clear disapproval. Del "Sonny" West, a member of Elvis Presley's "Memphis Mafia," appears in the supporting cast as a biker named Snake.