Krentz, Jayne Ann. Fogg Lake trilogy

"Thorndike Press large print basic"

"Decades ago, the Incident occurred: an explosion in the Fogg Lake cave system that released unknown gases. Afterward, some of the residents started having visions, while others heard voices--and the eerie effects also showed up in their descendants. Catalina Lark and Olivia LeClair, co-owners of a Seattle investigation firm, use their "second sight" to solve cases. When Olivia vanishes one night, Cat frantically searches for her friend. Then Slater Arganbright, an agent from a shadowy organization, shows up with a cryptic warning. A killer is hunting Catalina and Olivia, who are the only witnesses to a fifteen-year-old murder. Someone intends to make both women vanish."--Back cover