"The life of the famous Mr. Kent, the butler of the Mystery House, is in danger! Underworld kingpin Morton Mystery, the lousy sheep of the family, has kidnapped him and only agrees to return him in exchange for an investigation into the 'Christmas heist'. The fact is that on the night of December 24, someone robbed the museum and . . . framed Morton himself! Agatha and Larry are forced to get down to business . . ."--Google translation of synopsis from OCLC.