After Iranian nuclear scientist Kian Nouri falls to his death from his hotel room, Samar does not acknowledge that a joint Mossad-CIA venture ordered her to perform the hit. Red warns that an assassin known as The Scimitar has been hired to retaliate by targeting American nuclear scientists, so Agent Cooper orders a trio of physicists into protective custody. Liz goes to the abandoned ship where she presses Tom to name Berlin’s arms supplier. After Tom tells her it is Sevan Volkov, Liz arranges a meeting with Volkov and forces him to provide a lead to Berlin. Liz urges Ressler to get help for his addiction.
Believing the Iranians are tracking Jonathan Reese, the DSS agent tasked with protecting the scientists, Liz and Ressler intercept him at a parking lot, but are ambushed in an assault that causes their SUV to crash. Waking up in a hospital with a broken arm, Liz is told by a doctor named Rivera that she and Tom are being treated for their injuries, but that Reese disappeared. However, while Aram can’t find the agents at any hospital and Cooper is told that Reese isn’t with the DSS, Liz discovers that her arm isn’t broken and that she and Ressler are being held hostage. Disabling their nurse, Liz and Ressler look for a way out of the phony hospital room. Realizing that Reese was a fake persona used to expose Dr. Collins, Cooper and Aram head to the hotel, only to find Collins gone. Meanwhile, Red kidnaps Zoe in the wake of another conversation with her about her father.
After pressing Samar to identify Mossad’s target, Ali Hassan, Red reveals that The Scimitar - aka Walid Abu Sitta - is responsible for her brother’s death. As Red goes to see Hassan, Samar hurries to rescue Liz and Ressler before heading to the hotel. Arriving just as Collins is being wheeled out hidden inside a suitcase, Liz recognizes Dr. Rivera as The Scimitar. Though Liz recovers Collins, her captor escapes and heads for Hassan’s estate, where he finds Red waiting to turn him over to Samar. When The Scimitar says Samar’s brother was no innocent victim and that he knows she murdered Nouri, she kills him and dumps his body in the river where it is recovered by the FBI. Finally, as Ressler works to put his drug habit behind him and Liz heads back to the ship to see Tom, Red confronts Berlin when he arrives for the arms shipment. Though Berlin is intent on avenging his daughter’s murder, Red insists it’s all a misunderstanding and turns over Zoe, the original target of the vendetta, revealing that she’s not Red’s daughter, but Berlin’s.