The movie's structure is fragmented, as it alternates between three distinguishable plot threads.
A man jogging through suburban London grabs his heart, and collapses. He wakes up in a hospital bed. The nurse tending him give him water. She leaves. He pulls down the bed covers to discover both his legs have been amputated. He screams.
An official (Marshall Jones) from an unidentified Eastern European totalitarian state arrives back at his home country. Upon being debriefed by a superior officer, the man steps around the table, places a hand on the man's shoulder, paralyzes him, and kills him.
A Metropolitan London detective (Alfred Marks) and his unit, investigate the deaths of several young women in the city. The women, picked up at nightclubs by Keith (Michael Gothard), have apparently been killed by the same individual, and some of the bodies have been drained of blood.
The centerpiece of the movie is a near 15 min. long police car-chase/foot-chase sequence through suburban London.
Vincent Price plays a doctor whose clinic specializes in limb and organ transplantation.
Christopher Lee plays the head of Britain's -unnamed- intelligence services.
Peter Cushing -third-billed- plays an unidentified official in the Eastern European country; a very brief cameo role.
The three plot lines converge in a chilling - and unexpected - climax.
How many plot lines converge by the climax of the film?
three