Since her death and resuscitation, PI Harper Blaine has joined the ranks of the Greywalkers, individuals who can walk between the world of the living and the realm of the supernatural. When a boat named the Seawitch returns to Seattle after having been missing for 25 years, Harper assists the insurance company's investigation. Police detective Rey Solis is also assigned to the case and, despite his discomfort with the supernatural events associated with Harper, must work with her to solve a potentially deadly mystery.