The gang is on a stakeout, with Benson and Rollins in the surveillance van and Caresi in the brothel. Fin and Amaro keep watch from an unmarked car.
Benson recognizes the female handler, Selena. They helped her son get out of Mexico in the past.
They bust the place and make the appropriate arrests.
The owner of the brothel reveals that she's been tracking this specific trafficking ring in order to find her missing daughter.
Martha, said her daughter Ariel, has been kidnapped over three years ago, when she was only 13.
The squad tries to explain to Barba that Martha is innocent, but he isn't having it.
He demands Martha give up all her info, including her connect into the ring, so that Benson and the group can infiltrate the ring on her behalf.
Timmer, the pimp, is the man that they're after. Benson promises to help Martha get her daughter.
Rollins tries to comfort and talk to one of the 16 year olds they arrested. Caresi questions another, who refers to Ariel as "Snow Bunny" and says Timmer just beat her last night.
Amaro and Fin get some information out of Selena by mention her son.
The stakeout a new location where Timmer is supposed to be.
Carisi and Fin follow the car, and seem to lose it -- as Amaro predicted.
Rollins and Amaro keep an eye on the house, and find a truck distributing alcohol illegally.
Martha recognizes some women (Nina, one of Ariel's friends), and identifies Timmer from the pictures.
Amaro and Rollins realize that they can pose as the delivery guy and be the ones transporting the beer to the high class brothel event.
Amaro gets into the house and the rest of the team busts through the door.
Benson and Fin explain to Tracy that if she helps the event go through as planned and gets them what they want, she could work out a deal.
Benson, Fin and the gang get dressed up for the super bowl party and head out undercover.
They don't see Ariel, and Martha gets worried. Timmer said he'll figure out where Ariel is for the undercover Carisi.
Bishop, who's supposedly crazy, stops by and calls Benson and Fin intruders. He pistol whips Carisi for calling one of the girls a bitch, and then aims the gun. Benson pulls out her weapon and there is a standoff before the rest of the unit busts through the door.
Bishop is actually Lt. Declan Murphy, deep undercover.
He's pissed that they're blowing a huge undercover operation, and his fake Irish accent disappears. He says he's working for a "Johnny D" who's connected to hundreds of missing girls.
Even when they find the Johnny D's hideout through Timmer, they can't seem to find Ariel.
They finally find him in the back room with a piece of glass to Ariel's throat.
The safely reunite Ariel with her mother.
After Johnny D is sent to jail, Melinda comes over with some news for Benson.
Somehow, Johnny D is Noah's father.