Despite the evidence Liz has uncovered, Tom denies having anything to do with the murder of Russian agent Victor Fokin. As she takes him in for questioning, Liz learns that she’s been placed on leave until the investigation is complete. When she looks to Red for answers, he says the truth can be found by tracking down Gina Zanetakos, a corporate terrorist whom he says is Tom’s lover. However, as Meera grills Tom about why he was in Boston when Fokin was killed, Cooper reinstates Liz to help find Gina.
At a Washington, D.C., hotel, Liz and Ressler find that Gina’s latest contact, Turkish diplomat Nadeem Idris, has been killed. Though Ressler spots her and gives chase, in a vicious hand-to-hand battle Gina gets the upper hand and escapes. With evidence that Gina was hired to obtain a dirty bomb capable of contaminating a wide area with radioactivity, Liz and Ressler head to her apartment, where they find clues linking her to Tom and to Fokin’s murder. Though she’s unwilling to believe that Tom is involved, Liz does suspect Red of manufacturing evidence to manipulate her. As Liz tries to convince Cooper of Tom’s innocence, Red makes a deal with bomb maker Maxwell Rüddiger for information about the device Gina paid him to build.
Using a tip from Rüddiger, Liz tracks down Gina and wounds her as she tries to escape. With only four hours left before the bomb explodes, Liz and Ressler link Idris to a struggling company with a port in New Orleans. Realizing that the company’s fortunes could be improved if a competing port facility in Texas were rendered unusable, Meera questions Tom about the bomb as Liz and Ressler head for Houston. Suspecting Idris of using his diplomatic status to hide the bomb and expedite its shipment, Ressler finds it wired into a car with just minutes remaining before it explodes. With no time left to defuse it, Ressler drives the vehicle into the water, where it detonates without releasing any airborne contamination. Finally, when questioned by Liz, Gina says Tom had nothing to do with Fokin’s murder, even as she accuses Red of being involved.