Of course, Janet Greene is no Agatha Christie, but English female mystery playwrights were big in the 1950s. Her big play has more sociopathic psycho than most.
So, the big cheese to play the role was a perfect choice.
From light comedy to darkest character drama with sociological implications, Dirk Bogarde stormed onto the scene in British, arty films in the 1950s. He could play a charming medical students in the film series, Doctor in the House,or he could be a dangerous sexual predator as in Cast a Dark Shadow all within the same year!
No actor in the Hollywood system could do that sort of range.
In 1955, he managed to play one of his creepier wife-murdering fortune hunters, cast as the darkest shadow, Teddy Bare who is married to oldster Mona Washbourne. Her name is Moni, but it sounds like Mommy when Dirk speaks.
Moni makes a will, against Teddy’s wish. With no will, he receives all her money. He is forced to dispatch her immediately and must find another wife/victim.
In some ways, the young man after old ladies is not credible, but the idea of a young man hustling an older man was not feasible in 1955, but we give Bogarde credit for his unspoken suggestion. In one scene he is reading male health magazine with men in bikini photos.
That was about as blatant as you could be to send a gay message in 1955.
In glossy black and white, the film is a beautiful production with sharp sets and lovely photography from director Lewis Gilbert. The other women victims are younger and more apt, Margaret Atwood and Kay Walsh.
This is a lost gem that now is found on streaming services.