Based on a Leslie Charteris (The Saint) story, this French film (see the comment below for details.) the film is essentially a Saint movie in disguise at least in the American release which has the lead having a different name. The plot concerns a rich American who aids the police in "capturing" an American gangster (actually the gangster is killed). A year later the American is in France when he receives a letter threatening his life. Fearful that the police will not be able to protect him he hires a well known adventurer (Simon Templer or stand in) to provide protection.
This is a good, but not great, little thriller that feels almost like one of the Edgar/Bryan Wallace films that were being produced at the same time with a few horrific elements added in. Almost overly "twisty" the film at times to be over doing the mystery by over loading it with suspects and red herrings. Its not bad but its clear early on that the film is carrying a great deal of baggage that is there just to distract from whats really going on. The result is that you begin to disconnect since its clear the they are playing with you.
Don't let my reservations stop you. This is a good and enjoyable little film, as I've said before I wouldn't have taken the time to write up the film if I didn't like it. Its definitely worth your time if you run across it on TV or if you can find it on DVD (Sinister Cinema has it)