The basic premise was just a bit too off for me. I can understand Ben not knowing he had a son. As a social worker, Claire should have contacted him much sooner than she did - and certainly before the boy went into foster care, since she knew the dad was alive. I see where the drug runners came into things, but I doubt very much that the old boyfriend/survivalist would truly go through the trouble of kidnapping the child at all. I saw no real connection between Ben and Claire besides sex and if I were him, I wouldn't have trusted her at all. 
 With this whole series, it takes a long time for the story to get started - the first few chapters are all info dump - and then the endings get wrapped up really fast. The middle of the books often just aren't worth the bother.