Dead Time by Stephen White

Dead Time (Dr. Alan Gregory) - Four friends: Jack, Lisa, Kanyn, and Carmel along with Eric and his girlfriend Jules spend several days together on the floor of the Grand Canyon.   As they were preparing to leave, Nick approaches them saying that the girl he was with was missing.  Several years later, Eric is engaged to Alan Gregory’s ex-wife, Meredith.  Lisa has just become pregnant as a surrogate for Eric and Meredith.  Lisa disappears.  Meredith asks Alan to get Sam Purdy to investigate Lisa’s disappearance.  Alan and Lauren are adopting Jonas, the orphan of their neighbor who was killed in Israel.  Jonas’ uncle, Marty, is contesting the adoption.  Lauren is in Holland trying to find the daughter she gave up for adoption.  Grace is with her mother.