The evil Dr. Mabuse is after a scientists invisiblity formula to create an invisible army in order to take over the world. Thankfully a top FBI agent is on his trail. This film has good serial type thrills and is fun to watch if one is willing to suspend disbelief. Its great to see Lex Barker in a role other than Tarzan for a change. However, the poor English dubbing make his performance hard to judge.