Ariel's disappearance directly impacts the story, with The Executioner targeting four separate people connected to the Ariel Peterson case. Trent McBride, June Henry, Alison Sutherland, and Iain Vaughn.
After the disappearance of Iain Vaughn (he ran away but was caught by the killer), Ariel manages to escape captivity with the help of the police, and reunite with her mother, Heather Peterson.
Five years ago when Ariel was fifteen, she was walking home from a party where she was highly intoxicated. On her way, Trent and June; local paramedics, spotted her on the side of the road throwing up. Not wanting to spend another few hours filling in paperwork, the pair left the teen to her own devices.
Almost immediately after they drove off in their ambulance, a man we later find out to be Iain Vaughn, an off-duty police officer, offered her a ride back home to her parents. After getting her in his car however, he drove past her house, claiming to be taking her somewhere she could 'sober up' but raping and kidnapping her instead.
She was kept as a concubine in a room-sized safe in Iain's basement, where not long after being kidnapped, Ariel was impregnated, and gave birth to Iain's child - a boy called Jake. Other than Vaughn's infrequent visits and Ariel herself, it's likely that Jake has never seen anybody else.