When a family of hikers on the Appalachian Trail comes across the body of an 8-year-old kid, the BAU are brought in to profile and find the serial child abuser and murderer before he strikes again.
Joseph Lanham, the father of Daniel, the boy whose body was found, is an early suspect. Forensics shows that Daniel was killed right around the time Joseph gave up looking for him. But he is dismissed when Garcia helps uncover a string of other abductions up and down the trail, starting from long before Joseph and his family moved to the area.
Recently, though, the area of abductions and dump sites has been contained to a 30-mile area in Pennsylvania. The team theorizes that the abductor suffered some kind of injury, and isn't in good enough shape to hike the whole trail anymore.
The cases shifts into overdrive when young Ana and Robert Brooks, 9 and 10, are taken from their campsite in the UnSub's territory. After a night's fruitless searching, the team finally tracks them down to an abandoned coal mine in the hills. Brave Robert devises a plan that allows his sister to escape, but the UnSub (named Shane Wyatt) takes him to a nearby town.
The BAU track Shane to the house of drug dealer and pedophile Brandon Hayes, to whom he has traded Robert for a supply of painkillers. They recue the child, but Shane eludes capture and escapes back to the trail.