Changzhou Labor Camp, Jiangsu, China. The WHO is inoculating prisoners, in particular a young scientist named Xiaoping Li, who soon falls to the ground convulsing. One of the nurses claims Li is in cardiac arrest and must be taken to the hospital, so a guard finally relents. Three nurses rush Li's gurney onto an ambulance and pull out defibrillators as one of them radios into HQ, speaking perfect English. The ambulance is approaching the labor camp's gate when the guard realizes he's been played; this is an escape attempt. The nurses kick Li awake with a shot of adrenaline to her heart, promising she's safe. Tomorrow she'll be in D.C.
Across the world in Kraljevo, Serbia, the four menacing Pavlovich brothers get word of Li's escape from a client. Hezbollah will have to wait. They're on their way to D.C., where Liz is surreptitiously trying to bug Tom's key fob as he looks for his keys and grills her about Jolene - when did a missing persons investigation become a murder investigation? Later, Liz tells Red that Tom knows something's off - and why didn't Red tell her that Tom killed Jolene? Red explains that he called in the missing person report and wanted the situation to unfold naturally. Besides, Jolene undoubtedly worked for the same organization as Tom. Now it's time to wait and watch - which is why Liz needs a new case: the Pavlovich brothers are back in town.
It turns out the Pavlovich brothers are the same extraction team for hire that grabbed the general's daughter in the very first Blacklist case. Red's source informed him they're after immunologist Li, who was sent to the labor camp after she signaled she was ready to talk to the CIA and who is about to land at Langley. Cooper orders his team to reroute and meet Li's escort. But just as they arrive, the Pavlovich brothers snatch Li and take off in a helicopter, which turns up burning miles away and several hours later. Cooper wants to know why the Director of National Intelligence is calling, so Meera explains that the day before Li was jailed, she offered to share designs on a banned germ warfare project, code-named Whitefog. That's when Red calls, asking Liz to meet him outside the National Archives. When Tom called in sick to school, Red and his people tailed him there. Liz jumps out of Red's car and follows Tom into the Archives. She glimpses him refusing to take a package from a man we'll call the Professor, and she can't be sure whether they saw her. Meanwhile, the Pavlovich brothers drug Li and drag her to an abandoned warehouse.
When Liz gets home, Tom is waiting with the music box Red gave her. Where did it come from? Liz lies, claiming her father gave it to her. Tom lies back, telling Liz about his day, first to school, then on to the National Archives. Funny, he saw someone there who looked a lot like her - was Liz there? She denies it, so Tom leashes the dog, tells Liz he loves her and exits the brownstone. Moments later, Liz hears something outside, then finds Hudson sitting on the stoop. Tom rushes to a pay phone to say, "Mockingbird knows, request immediate evac," while smashing his cell phone. Devastated, Liz calls Red, who tries to explain this is all just business for Tom; time is the only thing to heal her wounds. Sick of waiting, Liz is determined to find Tom - but for now, she needs a lead on the Pavlovich brothers. While she returns to the Post Office to put the team on the trail of the helicopter, Red tracks down the Professor, who hands over Tom's package - a calculus textbook. The professor claims he's merely a courier, so after Xeroxing the textbook, Red instructs him to make a list of all drops to Tom, then make this drop per usual. It's not long before one of Red's guys tracks Tom to an old industrial building, rigged with several surveillance cameras. Now, how to extract him?
Aram deduces that the helicopter could only have come from Halifax Agro-Chem. Liz tells Red the FBI is going after Li at this location and orders him to back off Tom; she'll deal with him in her own way. The Pavlovich brothers are just stuffing a groggy Li into a wooden crate when Red shows up with a proposition. By the time the FBI arrives, the Pavloviches are long gone - and working for Red to execute a full-frontal assault on the building where Tom is being held. Tom and his handlers jump into two Mustangs for a crazy chase that ends with Tom exiting his car with hands up. Ressler is convinced Red played the FBI, so Liz, intending to call Red to ask for more help, returns home. There she finds Tom handcuffed to a chair, courtesy of Red and the Pavlovich brothers. Emotional, Liz demands answers: how could Tom ruin her life?! She demands he say something - anything - to his wife, who's dying in front of him. Claiming he was only doing his job, Tom tells her about a sweet, intimate moment between them when he knew "had her." Ressler calls, now convinced Red took Li with the intention of shipping her out of the country. Liz calls Red, who explains that Li is contraband, and nothing gets smuggled out of the Chesapeake without Rolph Cisco knowing about it.
Meera and Ressler speed to McKendrick Pier to intercept the Pavlovich brothers as they're transporting Li in her crate. Meanwhile, Liz has decided that it's time for Tom to talk - who does he work for? She breaks his thumb, which unfortunately enables him to slip out of his handcuffs and attack her. A furious and desperate physical fight ensues. Liz and Tom wreck their brownstone, and ultimately Tom gets the upper hand, cuffing Liz to the stairs. Claiming his job was never to hurt her and that he's one of the good guys, Tom warns that Reddington is not who she thinks he is. If she wants proof, she should use the blue key to open a particular safe deposit box. Red watches as Tom walks away, then finds Liz sitting in shock on her couch. Later, Liz returns to the storage unit and plucks the blue key off the wall. Whatever's in the safe deposit box proves a stunning revelation, but we'll have to wait to find out what it is...
While the FBI searches for a Serbian family of kidnappers, Red uses them in a scheme to out Tom, leading to a fateful confrontation with Liz.