During the World War II, the prisoners of a German camp in a Greek island are trying to escape. They not only want their freedom, but also seek an ineffable treasure hidden in a monastery at the summit of the island's mountain.

Demonstrating that a little knowledge is a dangerous thing, a convicted strangler studies the paranormal and finds a way to render himself invisible. Once he escapes, he sets out to find and eliminate five women who remind him of the mother he murdered. A police lieutenant sets out to safeguard them and bring the invisible killer to justice.