It is the eve of Madeleine Van Norman's wedding day. The beautiful young lady is soon to come into her family fortune, but she is found dead, apparently stabbed with an ominous blood stained letter opener. The police find everybody within the household a suspect, but there's a problem; Madeleine's bedroom was locked from the inside. How could a killer have entered or escaped? Could it have been suicide, as indicated by a note found near her body? An intriguing mystery ensues, hinged on the discovery of a single, all-important clue.