Benson wakes up bruised, bloody and tied to a chair. Her captor - Lewis, the perma-smirking sadist with a knack for sidestepping guilty verdicts - assures her no one's coming to save her. Not Cassidy, not the team, no one. He clocks her with the butt of his gun and she passes out again.
Back in the SVU squad room, it looks like Lewis is right - until Cassidy swings by to apologize for his no-show the night before. Suspicious, Cragen sends Fin and Rollins to Benson's apartment where they find every indication of Lewis' signature methods of torture, but no Benson. The team sounds the alarm and pulls Lewis' prosecutor girlfriend Vanessa out of court for questioning.
Vanessa presents the perfect alibi - she and Lewis spent the day together with her family. Turns out they did, but Lewis came back without Vanessa... to murder her father and rape her mother, forcing Benson to watch the latter.
On the road in a stolen car, Lewis keeps cool - jolly, even - with Benson drugged under a tarp until a rookie cop stops him for running a light. The cop presses a little too much and Lewis unleashes - shooting him in the head at point-blank range. By the time SVU finds the body, Lewis and Benson are long gone, holed up in a remote beach house.
Lewis cuffs Benson to an iron frame bed as she challenges his sick resolve, baiting him with offers of pleasure, pain, whatever will satisfy him. Just as he unbuckles his belt, Benson dislodges an iron bar from the bed and - summoning all her strength - cracks it across his face.
Moments later, with Lewis cuffed and unconscious, Benson paces the room, fantasizing out loud about what she could do to repay him for the dead bodies, the rapes, the torture. Blowtorch, maybe? It's hard to decide - Lewis says as much when he awakes and taunts her to act on her emotion. Benson struggles to resist while he waxes poetic on his sordid past - how rape was a family trait - and insults her conviction. Her rage boils over and she again grips the iron bar, pummeling Lewis in a fury of anger and catharsis.
After Benson calls in SVU to arrest Lewis, Cragen reminds her she can't return home - it's a crime scene. She turns down a hotel room in favor of Cassidy's apartment, but Benson's face indicates no sense of relief. That same concern travels with her when she sits down with a psychiatrist and confesses her worry about Lewis. "He got to me..."
Two months later, Benson is still struggling to recover from the trauma, despite regular therapy sessions and self-defense training. But this is Benson - SVU is her life - and she returns to the squad early, eager to put her recent past behind her.
She pounces on the first case through the door - a lost seven-year-old, Buddy, ditched by his father in the middle of Times Square. Seems easy enough, until Benson interviews him and finds out he doesn't even know his father's name or his own address - what's this kid holding back?
The SVU team ekes out enough information to backtrack to Buddy's house, where they discover a basement divided into three caged cells - the only occupant a young, whimpering woman chained to a wall. Turns out she's a missing person from 2002 and just as developmentally stunted as Buddy, mentioning the same trio of unknowns - "Ma," "Pa" and "Sissy" - and confirming rape.
Fin and Amaro drag in the homeowner only to find out he hasn't lived there for years - someone must be impersonating him. When SVU gets word of skeletal remains, Benson simmers, certain that the perp shares the same kind of demented MO as Lewis. Before Cragen can calm her down, more news arrives - someone found Sissy.
Just like the other caged victim, Sissy's a missing person, but lucky for SVU she can form complete sentences. She details her kidnapping, the frequent rape - how Pa preferred her to the other girls - and that Buddy, unbeknownst to him, is her child with Pa.
As this sets in, Fin and Amaro locate Ma and quickly determine she suffers from Stockholm Syndrome - an undying loyalty to Pa despite his regular abuse. Whenever Pa left the house, Ma had free range, a fact that rubs Benson the wrong way. She refuses to let this point go during the Ma interview and totally cracks - yelling at Ma, out of control - and Cragen pulls her from the room, demanding that she return home. "It was too soon for you to come back to SVU."
Ma flutters at the sight of Buddy's drawing and eventually reveals her real name, a lead that Fin, Amaro and Rollins use to track down Michael Williams - aka "Pa" - at his home in Greenpoint... a home he shares with a wife and two children, all oblivious to his crimes.
Fin and Amaro press Williams for a confession, but he's clearly psychotic, maintaining that he "helped" the women he imprisoned and abused. D.A. Barba, disgusted by the affair, guarantees Williams won't see the light of day. Later, Benson shares a moment with Sissy, reunited with her son yet fearful of the future. Benson assures her things can - and will - change for the better. Advice, it seems, that applies to Benson, too.
As Benson struggles to free herself from the clutches of a sadistic killer, the SVU squad scrambles to find their location before it's too late.