Killer's Moon (1978)

Four mental patients, the products of illegal medical experiments, escape from an institution in Britain's rural Lake District. Armed with a stolen axe, they kill a game warden and mutilate a dog before encountering a broken-down bus. The vehicle's stranded female passengers search for a place to spend the night, unaware that the psychopaths are right behind them. Anthony Forrest and Tom Marshall star in this notorious 1970s cult classic slasher!