>> reporter: what began with fire became murder and manhunt. >> the level of intensity in this investigation is incredible. >> reporter: a best friend turned worst enemy. >> this gentleman was a friend of ours for a long time has taken everything. >> reporter: hundreds in desperate pursuit of one teen in grave danger. >> the amber alert was on. i see a picture of this blonde-haired girl. i said that's the girl we've seen up on the mountain. >> reporter: kidnapped, the rescue of hanna anderson. it was going to be a normal summer weekend, pop warner football for ethan. cheering practice for hannah. a road trip for the dog and mom christina to jim's house.