The Edge (FBI Thriller, #4)

FBI agent Ford "Mac" MacDougal is recovering from injuries he received in a terrorist car bombing when his sister, Jilly, a medical researcher, drives her Porsche off an Oregon cliff - on purpose, it seems. Curiously, even though he was in a hospital bed on the other side of the country, Mac feels as if he were in the car with her as she sails towards the sea.
By the time Mac arrives in Portland, Jilly has come out of the coma she's been in for four days. But after only a few hours with her brother, she vanishes without a trace. In searching for her, Mac hears a different story from everyone he encounters. When the local sheriff enlist his aid in the puzzling murder of an elderly resident, Mac doesn't suspect that the case connects to his sister's disappearance. FBI agents Lace Sherlock and Dillon Savich (last seen in The Target) join Mac to ride shotgun. Not knowing whom to trust and whom to suspect, they must escape relentless pursuers before unearthing the tentacles of evil undermining The Edge.