Henrietta Winslow, a
cat lady, calls her family to her estate. Seeing their arrival, realtor Gil Smith and antiques dealer Mr. Penny sneak onto the estate. She leaves half her fortune to her niece Myrna, the other half to her granddaughter Margaret, and the estate to her granddaughter Elaine. Myrna's husband Montague gets $10,000. The interlopers are brought inside after Gil's cat
allergy exposes their presence. Henrietta is furious when she realizes that Montague sent for them and intends to break up the estate. Gil prevents Henrietta from being poisoned. She then reveals that the money will not be distributed until the servant Abigail also dies. That night, one of Henrietta's cats is poisoned. She cremates it, and is herself killed. Abigail orders everyone off the estate, but they refuse. Montague's son Richard discovers that he is having an affair with Margaret and threatens to tell Myrna. Abigail is attacked, and Gil suspects that
secret passages are allowing the murderer to move around. Gil and Elaine investigate several nighttime disturbances, all of which are
red herrings. Abigail is found murdered. Gil, Montague, and Richard find Myrna hanged, but save her life. Gil and Montague chase the butler, but Elaine accuses Myrna of faking her attack. Myrna drags Elaine to the furnace, but Gil saves her. A black cat knocks over a candle, setting Myrna on fire. Afterwards, Elaine lets Gil sell the estate. ==Cast==