A woman private eye in a man's world, Molly Murphy is having a hard time succeeding as a New York shamus. That's why she agrees to go undercover for the NYPD to expose a pair of spiritualist sisters as con artists even though the offer comes from police captain Daniel Sullivan. Sullivan had once won Molly's heart—until she discovered he already had a socialite fiancée and an upcoming wedding.
Now Molly's masquerading as a cousin from Ireland at the Hudson River mansion of Senator Barney Flynn. Flynn's invalid wife hopes the psychic sisters can contact her dead son, kidnapped and lost in a sensational crime. After an eerie séance, Molly isn't so sure the sisters are fakes, but she's certain the police bungled the kidnapping case. Soon Molly's questions are leading her toward danger, and her own sixth sense is warning her—murder lies ahead!