Twenty nautical miles off Boston, fogbound Bell Island is known for spirits and other, less easily named presences, and for a past that sheltered women fleeing the Salem Witch Trials before serving as a way station on the Underground Railroad.
Microbial biologist Harper Hafdóttir comes ashore in search of Thalassa, a possible new species of octopus, carrying old trauma and dreams that keep returning.
Unexplained seismic activity, a rogue wave that capsizes a boat, and encounters with island creatures she cannot account for lead her to Lady Loreana Bell, the mayor whose family has ruled through a single matriarchal line for four hundred years and who seems already to have expected her.
In gothic Bell Manor, Harper is overtaken by déjà vu and uncovers the 1690 journal of a young woman caught in a religious cult.
With a tsunami closing in, she stands near a revelation that may finally clarify her haunted dreams and her true purpose on Bell Island.
