A master crook, known as "The Bat" because of his disguise, announces a jewel theft in advance but is foiled by a rival crook at the scene of the crime. Their trail leads to the Courtleigh Fleming estate, now leased to Cornelia Van Gorder, a wealthy spinster. The reported death of banker Fleming and the disappearance of Brooks Bailey, a young cashier in love with Dale (Miss Van Gorder's niece), add to the complications of a $200,000 bank robbery. Brooks, masquerading as a gardener, remains concealed in the house, hoping to unravel the mystery. Lizzie, a servant, suspects everyone, including Dr. Wells, the butler, and Detective Moletti. The Bat, who has killed Moletti and is impersonating him, is finally captured in a bear-trap.