Glynis Johns is the sort of sweet but vague woman who calls everyone 'darling'. So when a dead man turns up behind the couch, she calls her houseguests and has them move the body into the secret passage in the house.
It's based on one of Agatha Christie's lesser known stage plays. Like most of her writing, it is marvelously plotted, but indifferently written. It relies on a fine cast to bring this murder mystery to life, including Jack Hulbert, Cicely Courtneidge, Ronald Howard, Ferdy Mayne, and Peter Butterworth as the befuddled inspector.
It's been opened up slightly from the stage play, resulting in a four-set movie.
Sometimes it seems as if makers of mystery movies have two choices: they can make a good mystery or they can make a good movie. This one is enlivened by a fine cast, but not enough to make it more than an indifferent programmer.