While Liz wants to question Naomi about Berlin, Red insists she investigate a series of deadly rampage killings he suspects are linked to a secret government mind control experiment. After DNA tests reveal that the attackers all possess a rare gene that makes them susceptible to violent, antisocial behavior, Cooper confirms Red is telling the truth and sends Liz and Ressler to see Senator Donovan Sheridan, whose committee oversees the black budget operation known as Subproject 7. Meanwhile, after telling her new husband Frank about her past with Red, Naomi insists that they resist any efforts to relocate them. As a result, Red threatens to expose damning secrets about Frank’s life unless he can convince her to move someplace safe.
Because the documents provided by Sheridan are heavily redacted, Red and Liz turn to a code breaker whose version of the Subproject 7 file identifies Dr. Linus Creel as the scientist who is secretly re-engineering the brains of his subjects to turn them into killers. Using a fake medical history that makes her look like a likely candidate for his study, Liz helps Aram hack into Creel’s computer to get the name of his next subject. Finding evidence that he’s manipulating Duncan Prince to go on a killing spree, Liz and Ressler arrive at a community meeting in time to save Senator Sheridan from being his next target. But after he’s wounded by a shot from Prince, Creel takes Liz hostage, only to have the mysterious sniper Red hired to follow her cut him down.
After Samar gives her a file Creel had been keeping on her, Liz uses a tip from Aram to find the safe house where Naomi and Frank are staying. While Liz is certain they are connected through Naomi and Red’s daughter, Jennifer, she’s warned that Red isn’t who he says he is. But when Red shows up to stop Liz from asking any more questions, Naomi leaves with Frank after telling Red she has no idea where Jennifer is. Finally, when Liz demands that he call off the sniper’s protection, Red suspects she’s hiding something.