Ian Norville, an autistic boy, goes missing while on a school trip to the Natural History Museum. Jack instantly suspects Ian's father, Daniel, after he exhibits some odd behaviour immediately after the disappearance. It is speculated that following some recent revelations in the Norville family home, Daniel may be relieved that Ian is missing, and perhaps even personally involved in the disappearance. As the team investigate further, they suspect that various people close to Ian could be involved. They also learn how difficult it is to raise a disabled child, both for the family, and the child itself.
