Castle and Beckett's foray into enjoying a little afternoon font (they were mapping out their "save the date" card) is interrupted by a call from Captain Gates. Something has happened. Gates needs to see Beckett alone. The head of narcotics, Captain Fowler, produces pictures of six slain mid-level drug dealers. There's a new drug ring in town. They are pretty much invisible. The one thing that is known about them is the name of the leader-Lazarus.
A Russian woman named Elana Markov was lured into the drug ring. She claims everything she did was done so anonymously. The drug ring wants to offer this woman a promotion. Unfortunately, she recently tried to commit suicide. Beckett has a similar look to the woman, and she speaks Russian. The narcotics unit wants her to go undercover to help them bust the ring. Beckett agrees to go to a meeting at a hotel. Plain clothes cops are spread throughout the place. That doesn't stop the bad guys from pulling a gun on Beckett in the elevator. She's kidnapped. No one has any idea where she is.
Gates doesn't care for Fowler's plan for a limited alert. She wants to call in the cavalry, aka Ryan and Esposito. A worried Castle is at home with a feeling that something isn't right. Beckett is brought before a Mr. Jones, who says it's good to finally meet her. Beckett's kidnapper goes by the name Harden. A permanent position in their organization is offered to her for $50,000. Beckett wants to meet Lazarus. She realizes that Elana is not some low-level courier as she was told. Beckett manages to call the precinct while Harden is out telling Jones that he has a bad feeling about the woman they've brought in.
Gates gives Castle the scoop on what's happening. Ryan and Espo head to the hospital to question a now-conscious Elana. The woman is gone when they arrive. The cop who was guarding her is dead. Esposito and Ryan fear Beckett's cover is blown. The drug ring is going to kill her next. Beckett realizes she may soon be out of time. She hides a farewell letter to Castle letting him know that she loves him with all her heart. Always.
Lazarus agrees to meet with Beckett as long as she completes an assignment. She's instructed to do what she does best. She's told to kill a man. Beckett is denied information on the background of her target. She enters the man's home. Two silent gunshots are fired and then she's back outside. Harden demands to see the body. Beckett obliges. It's a gory scene that's enough to satisfy Harden. The dead guy, Evan Potter, isn't really dead. He simply followed Beckett's instructions until it was safe to call the police. The guy is a corporate lawyer with no ties to the drug ring.
Beckett is returned to the compound where she is being held. She tries to use a party girl's phone to call for help, but is interrupted when meeting time with Lazarus arrives. Beckett sees dozens of barely-clothed women using counting machines to tally what has to millions in cash in the basement. When she's finally brought inside to meet Lazarus, the man knows she's not Elana. In fact, he knows exactly who she is. He tells Beckett that the last time he saw her she tried to put him through a wall and accused him of murdering her mother. This man is drug lord Vulcan Simmons, who was first seen in "Knockdown."
Beckett is tortured by having her head held under water. Vulcan Simmons taunts her by bringing up her mother's fate. Then more water torture. Beckett is near death as her team desperately tries to hone in on a cell phone signal. She's led into the woods by Harden after Vulcan gives the order to burn the compound. Beckett is about to be killed when the real Elana shows up to cut Harden's throat. She says Lazarus wanted her to live because he owed her.
By the time tactical teams raid the compound, everything is gone. Vulcan Simmons is questioned by the authorities, but he has an alibi. There's no way to prove the money laundering operation Beckett witnessed ever existed. There is one lead. Beckett noticed the money was being funneled into an account labeled "Future Forward." Speaking of the future, Beckett lets Castle know that what kept her alive was the thought of her life with him. She also knows that Vulcan Simmons is not Lazarus. If he was, she'd be dead.
Someone else is behind the ring Beckett witnessed. Someone bigger. Future Forward is a political super PAC. The would-be murder victim from earlier, Evan Potter, did all the legal work to establish it for a wealthy client named Jason Cokeler, who just died of a heart attack. Millions was laundered through the super PAC. Someone is using the money to build a massive political war chest. Beckett knows that it's Senator Bracken. Now they have each saved each other from being assassinated. Now they are even.