Mac arrives in Portland, his sister - Dr. Jilly Bartlett, a medical researcher - has come out of the coma she's been in for four days. But after a few scant hours with her brother, Jilly vanishes without a trace. In searching for her, Mac gets a different story from everyone he encounters. When the local sheriff enlists Mac's aid in a puzzling murder of an elderly resident, Mac little suspects that the case connects to his sister's disappearance. FBI agents Lacey Sherlock and Dillon Savich (last seen in The Target) join Mac to ride shotgun, only to find their search leading from a small town on the Oregon coast to the rain forests of Costa Rica. Together, they must escape relentless pursuers as well as the hostile jungle itself before discovering the true nature of the evil at The Edge.