Prigionieri dell'eternità was released in the year 1957。Prigionieri dell'eternità is also called as The Man Who Turned to Stone, Tuchthuis van de angst, Pénitencier de la peur。

A group of 18th-century scientists, led by Dr. Murdock, have remained young after all these centuries by using electricity to suck the life out of young women. If one of the scientists misses a treatment, his skin hardens to the toughness of stone. A female prisoner discovers why so many of her fellow inmates are disappearing, and attempts to stop them with the aid of a prison psychiatrist.