Olivia gets the call that Noah is missing. She frantically asks Finn which precinct is closest to Mall of Manhattan then runs out the door.
At the mall, security is reluctant to lock down the premises but Olivia insists. The investigation begins. Sheila tells Olivia she doesn't remember anything except a guy with mutton chops and insists she didn't do this herself.
Dodds calls FInn and orders Olivia stay off the case. Finn reluctantly relays the message, which Olivia ignores, running the investigation from home.
Finn and Sonny interview the mutton chops guy and find out he was trying to hit on Sheila. Other witnesses help them discover that a Latino guy took Noah. They find Noah's coat in the trash and get security footage that shows the guy changed Noah into a blue sweatshirt and put him in the back of a car. Noah didn't appear to be afraid.
The car that Noah was taken in is found abandoned by a bus depot in New Jersey. Sonny and Rollins interview a clerk at the bus station who claims Noah and the man got on a bus that is conveniently stuck in traffic 10 miles away. They rush to the scene but there is no sign of Noah on the bus and the driver claims he was never there. Meanwhile, Sheila and Olivia jointly freak out after Sheila claims not to know who the guy who took Noah was.
Finn talks to a car dealer and finds out the kidnapper had a brand new baby seat that he tried out in the kidnap car before getting it. He finds the box in the trash. They trace it to a store and find out that Sheila bought it.
Sheila has gone home, supposedly. Olivia fills in the others and they go to the house but do not find anyone. Olivia knows Sheila is gone for good because she took her photo of Elly with her.
Olivia worries that Sheila could be anywhere. Meanwhile, Sheila gives Noah fast food and pretends to call Olivia to say she is checking in.
Barba comes to see Olivia, who does not want sympathy. Olivia feels stupid that she trusted Sheila with Noah. Through talking to Barba, she realizes the only other person Sheila knew was her lawyer for the custody battle. Barba goes to see the lawyer and gets her to tell him who the PI who referred Sheila was. The lawyer reluctantly gives the info.
Finn interviews the PI who claims not to know anything about the kidnapping. The investigation leads them to Juan, the actual kidnapper, who is Sheila's gardener in New Hampshire.
Rollins and Carisi pay Juan a visit. When he won't talk they randomly arrest his daughter for conspiracy to commit kidnapping even though they know she was not involved in order to force him to talk (yeah that would fly). He tells them he was supposed to meet Sheila and Noah in Montreal and claims Olivia was abusing Noah and didn't love him. He is arrested and takes them to the cabin he gave to Sheila, but no one appears to be there.
Olivia breaks into Sheila's cabin but Sheila jumps her and makes her drop her gun (because this hasn't happened a million times before already). Sheila holds Olivia at gunpoint and insists she is Noah's mom and that Olivia can just adopt another baby since she's not really Noah's mother to begin with. Noah wakes up and is happy that Mommy made it to the cabin. Sheila sends him outside and says Olivia can't have him. They struggle and Sheila cries and Olivia subdues her.
Sheila is arrested and taken to a local precinct. Olivia ignores her apology.
Noah seems to be just fine and happy that Uncle Sonny and Aunt Amanda are taking him home. He doesn't seem to wonder where Grandma went.
Dodds comes to see Finn who says Olivia followed orders and stayed home alone by the phone the whole time Noah was missing. Dodds is glad Finn is on the side of the good guys.
Barba comes to check on Olivia, who isn't sure how she is doing. He comes in and joins the playdate that Noah is having with Amanda, Sonny, and Jessie. They all build robots together.