Fear in the Night (1972)

Mr Dear John himself, Ralph Bates, plays a newly-wed schoolteacher with a quaint blonde wife who thinks she's being stalked by a one-armed man.
It’s an unusual film for Hammer studios to have made in the 70s, because it’s a straight up psychological horror not a supernatural one.
It’s not as menacing as the Italian giallo style movies that it takes influence from, but I urge anyone who gives it a try to stick it out to the end because the last third is where all the good stuff happens.

3½ twists of the wrist out of 5