When retired merchant J. T. Manly is murdered, his son James, with whom he had quarreled, is arrested and finally convicted through the testimony of Manly's valet Aguinaldo. Shortly before James's execution, Sidney Holmes reveals to retired criminologist Martin Cross that on the night of the murder, he saw Aguinaldo commit the crime through the bedroom window of his friend Robert West's wife Helen. Although his presence in Helen's room was innocent, he refuses to make a public statement that might besmirch her honor. With this knowledge, Cross hires a fake spiritualist to terrorize Aguinaldo with contrivances of ghosts, skeletons and mysterious faces. The ruse is successful, and Aguinaldo confesses that he killed Manly to avenge his mother, whom the merchant had wed and later abandoned. Robert dies, leaving Helen free to marry Sidney.