Despite still blaming him for framing her husband (Ryan Eggold) for murder, Agent Keen (Megan Boone) is forced to work with Reddington (James Spader) to take down a member of The Blacklist responsible for the chemical attack on Washington D.C. subway by a chemical engineer named Frederick Barnes (Dr. James Wilson) who has very personal reasons for unleashing a rare disease upon the populace. Keen and Ressler (Diego Klattenhoff) talk with the man’s former research partner (Amy Hargreaves) whose son suffers from the same rare disease Barnes weaponized and unleashed in the subway and learn the scientist is actually the boy’s father and was turned down for research grants to cure the disease when it was determined it was too rare to justify the funding.
Reddington heads to Cuba, sadly without Keen, to talk with a middle-man (David Zayas) supplying the scientist with radioactive materials in order to track down Barnes but not before he deploys another bomb inside an Arlington courthouse. The good doctor also pays a house call to the only survivor of the latest bombing whose natural immunity to the disease is the first step to Barnes synthesizing a cure. Of course to administer it he’ll have to kidnap the boy.
The B-story involves Luli (Deborah S. Craig) and Dembe (Hisham Tawfiq) acquiring a home from Reddington’s past which also involved a young girl who appears in a flashback not unlike what a young Lizzie must have looked like all those years ago continuing to foreshadow a familial bond between the agent and criminal.
The episode ends with Lizzie’s attempt to reverse her earlier mistake of letting the scientist go when he grabbed a hostage at the courthouse. This time Keen chooses to kill him before he can administer his new cocktail to the boy. Despite Ressler’s approval of the second situation, one could certainly argue she made the wrong choice both times. Before the night is over Reddington also offers Keen a deal to disappear and withdraw his help if she tells him to leave which is the one thing the curious profiler can’t bring herself to do.