 Seismologist Alice Bradley is despatched to her home town of Baie-Comeau, Quebec, to investigate why the tides have stopped flowing there. She is reunited with an old college friend, reporter Catherine Rolland, and meets roguish pilot Marc Vandal. It soon becomes apparent that the problems with the tide coincided with a variety of odd behaviour amongst the Baie-Comeau residents, and Alice gradually realises that the solution to the mystery may be stranger than she ever anticipated.