It's one of Dennis O'Keefe's latter days movies, but Anton Diffring steals the show from him ,in his portrayal of
an almost mad philatelist who would do anything to get an invaluable stamp, a genuine item O'Keefe bought in an auction sale ; the stamp collector is so lured by this rare item he accepts to become a hired killer.
The title sets the tone: the lady seeks vengeance ; but as she threw herself under a train, it's her guardian who is asked (by a beyond the grave letter) to do the job.
The movie sometimes drags on (and the female part is insignificant) but the last fifteen minutes will keep you glued to your chair ; the lady seems to have risen from the dead to enjoy her vengeance ; the recorded tape adds to a fine suspense .