Overview
Psychomania (originally released in the United States as The Death Wheelers) is a 1973 British outlaw biker horror film starring Nicky Henson, Beryl Reid, George Sanders (in his final film) and Robert Hardy.
In the film, the adolescent leader of a biker gang has started practicing black magic. After meeting the Frog God which his mother worships, the leader commits suicide on his 18th birthday. His mother resurrects him as one of the undead, and the process grants superhuman abilities to the boy. He proceeds to turn most of his gang into fellow undead, but his mother petrifies them all in a magic ritual.
Plot
Tom Latham, an amiable psychopath and the leader of a violent youth gang named "The Living Dead", enjoys riding his motorcycle with his girlfriend Abby and loves his mother. Tom dabbles in black magic and spends much time at an ancient ruin located in the Surrey countryside known as "The Seven Witches" (a Stonehenge-like circle of standing stones). In a similar vein, his mother and her sinister butler Shadwell get their kicks out of holding séances in their home while they worship some sort of Frog God. Tom's father vanished in a mysterious room shortly after Tom's birth, a room which Tom enters on his 18th birthday and where he sees the Frog God.
This incident leads to Tom committing suicide and, with his mother's help, Tom returns from the dead. Being one of the undead means that Tom cannot be killed and has superhuman strength, which he demonstrates when he massacres the people drinking at the local pub. One by one, his fellow bikers commit suicide with the goal of returning as one of the "undead", gathering at "The Seven Witches" to plan their campaign of terror against the locals. Only Abby refuses to commit suicide.
From Wikipedia (CC BY-SA 4.0).