This British film begins with learning that Mr. Clavering (Sidney James) is a follower of Eastern mysticism and is married to a horrid second wife, Bertha. He knows he's dying and decides to try out a particularly difficult and dangerous stunt...to put himself into a death-like trance. He demands absolute silence...claiming it could be fatal if anyone makes any noise. During this exhibition, a painting falls off the wall...and Clavering appears to actually be dead!
When the will is read, the bulk of the estate is to be given to Clavering's daughter from his first marriage, Joan. However, Bertha and her viper-like daughter are allowed to stay in the house and the will stipulates that Bertha is to advise and oversee Joan until she reaches 21. Bertha instead decides her best route is to instead try to drive Joan mad and take the fortune for herself! To do so, she begins 'gaslighting' Joan. In other words, acts as if things are just fine and gets Joan to doubt her own sanity. To assist, is a particularly vicious thug, Victor. So what's next? See the film.
I give this film kudos for being darned clever. The script is very well written--with nice unexpected twists, a terrific ending and wonderful dialog. All in all, a nice little suspense film that manages to offer a few genuine surprises.