Make Haste to Live (1954)

Crystal 'Chris' Benson, a single mother in a small New Mexico town, senses a shadowy menace stalking her in the night. She acquires a gun and makes arrangements anticipating her own death, tape-recording a message for her teenage daughter which (in flashback) tells of her involvement with Steve Blackford, who has very good reason to hate her. Chris is determined and resourceful, but Steve has had 18 years to plan revenge. Doom closes in...