This movie follows the story from previous versions and play presentations. Looks like a lot of out of work actors including but not limited to Honor Blackman, Wendy Hiller, Olivia Hussey, and Carol Lynley.
The story starts out with an unnecessary introduction of want is to come with a hanging cat.
Just as a play only one person talks at a time. Each character is introduced and their peccadilloes explained. The dialog shows to be an attempt at humor. It also clings closely to one-liners as the Bob Hope version (1939) set in the 1920's. One added plus is that the credits showed the faces of the actors with the names; it is rare but keeps you from having to second guess who plays whom.
1934 20 years after old Cyrus West (Wilfrid Hyde White,) very a rich old man kicks the bucket, his will is about to reveal his heir. If the recipient proves to be insane or also kicks the bucket, then there is a second heir. To make things more complicated there may be a loose lunatic that escaped from a nearby asylum; they call him the cat.
Remember as Bismarck said "a little caution outflanks a large cavalry"