Benson and Calvin attend a Halloween festival while Amaro quibbles with his daughter. Rollins and Fin bust a pedophile who's handing out treats. Across town, Allie purchases organic diapers for her baby, Nate. When she returns to the parking lot, her car - and her baby - are gone. The SVU team learns that Tim and Allie are tourists. When Allie tells Tim what happened, he explodes into a rage. Tim tells Amaro he found a place on Craigslist, but when he got there, six tenants were already staying there.
Cragen tells Benson and Amaro that Tim has a domestic abuse charge on his record. Allie's sister called it in because Allie refused to cooperate. No charges were filed. Later, Amaro asks Allie about the domestic abuse charge. Allie says it was nothing and that her sister overreacted. Tim tells Benson a similar story. It was a minor fight, and Allie's sister and mother made it into a scandal. Cragen gets word that the car has been found. Unfortunately, Nate and his kidnapper are still missing.
Allie tells Amaro that she and Tim drove in from Buffalo for the Halloween parade. Later, Rollins and Fin talk to Moira, Allie's sister. Moira says Tim and Allie live separately and that Allie lives with her. She describes Tim as a jealous drunk who was abusive to Allie. Benson talks to Tim. He says he worries that Allie will blame him for Nate's disappearance since Tim wasn't there when Nate went missing. Later, Mr. Hernandez brings in Nate's car seat, claiming a peddler sold it to him at Tompkins Square.
Benson and Amaro talk to the Tompkins Square peddler. He admits to breaking into the locked car and says he stole the car seat. He says he didn't see a baby. Later, Amaro makes a chilling discovery: fecal matter was found in a cooler in the car. Was the baby's body stowed in there?When Benson shows Tim a photo of his cooler, Tim looks visibly upset. When Benson implies that Tim may have killed Nate, Tim explodes in another rage. Meanwhile, Allie admits to Amaro that the night before Nate went missing, they stayed in a motel. This contradicts Tim's story that they slept in their car.
Rollins and Fin talk to a motel employee about Tim, Allie and Nate. He says the couple barely paid any attention to their son while they partied at a bar. Allie admits that Tim was drinking the night before Halloween. Later, Tim tells Benson that he and Allie fought over Nate's pumpkin costume. He didn't think it was the right costume for Nate. Finally, Amaro says he got Allie to admit to where they buried Nate. On a remote beach, the team finds Nate, dead.
After further interrogation, Amaro tells Allie that Nate died of Sudden Infant Death Syndrome. Surprisingly, it's a relief to the couple. Tim was too drunk to recall exactly what happened, and Allie thought she had done something wrong. Allie thought nobody would believe it due to Tim's domestic abuse charge. She admits they put Nate in the cooler and then buried him.