A greedy family led by Montague Hartley (Basil Rathbone) wait for the death of Henrietta Winslow (Cecilia Loftus) so that they can inherit her fortune. However they discover that they can't until housekeeper Abigail Doone (Gale Sondergaard) and all her cats die. When Henrietta is later murdered the race is on with the help of two antique dealers Hubert Smith (Broderick Crawford) and Mr. Penny (Hugh Herbert) to find the culprit.