Some interesting ideas...
but I really didn't like the misdirection at the beginning with the bike.
Major spoilers below ***************
So the two children that managed to escape from the abductor however many years ago just agreed it would be better to not talk to police and make up a nonsensical story about a magical house in the trees. This made it sound like they're suffering from PTSD related fantasies to throw the police off from asking questions in order to wait x number of years for one of them who is arguably less screwed up to come back for vengeance. They were able to think this far ahead. Riiiight. And the other one that supposedly scarred up his own face, wtf was that about? Not to mention his reaction when his abductor came to visit him in an official police capacity. No one found that odd? The abductor's police partner, the parents? I appreciate there will be some type of link to the guy due to the traumatic events of his childhood, but come on.