This is probably the first entry in the "Lance O'Leary/Nurse Keat" detective series; in subsequent O'Leary films, he was played by much younger actors than Guy Kibbee.
A group of relatives (all played by well-known character actors) gathers in an old house (on a rainy nite, of course!) to speak to a wealthy relative, who goes into a coma.
While they wait for him to recover, all sorts of mysterious goings-on happen, including a couple of murders.
A creepy film; worth seeing!