A secret agent possesses a ring that makes him invisible for a short time, once every 10 hours. He is in pursuit of an evil criminal mastermind but, at the same time, must evade an enemy agent who also wants … Patrick O'Neal, Ira von Fürstenberg, Donald Pleasence, Henry Silva, Nicoletta Machiavelli, Howard St. John, Sorrell Booke Added on Amazon Prime 2023-09-22.