A writer who studies the paranormal believes that low frequency tactile sound is the cause for reported ghost sightings in an abandoned subway station. In an attempt to debunk the sightings, she breaks into the station to record evidence.
A hardened New Orleans cop, Dave Robicheaux, finally tosses in the badge and settles into life on the bayou with his wife. But a bizarre plane crash draws him back into the fray when his family is viciously threatened.