In Weymouth, Massachusetts, a FBI assault team closes in on a pier. A truck pulls away and they cut it off. The truck doesn't contain the illegal goods they're looking for. The team leader, Mitchell Loeb, reports to Broyles saying that the man in charge, Joseph Smith, has disappeared but someone knew they were coming. As Broyles notices a seven-pound weight discrepancy in the container, Mitchell collapses to the floor, writhing in pain. They take him to the hospital and prepare to operate while Broyles tries to reassure Mitchell's wife Samantha. The surgical team opens Mitchell up and finds a large parasite inside his chest cavity, wrapped around his heart.
Broyles calls the team in to see the parasite. Walter doesn't recognize it from his experimentation but believes it to be some kind of genetically-manipulated creation. They take Mitchell back to the lab and while Walter prepares to operate, Samantha comes to see Olivia to find out what's going on. She also turns over a piece of paper covered with numbers that Mitchell brought back with him.
Walter manages to extract a skin sample from the parasite but it constricts around Mitchell's heart. Peter manages to keep Mitchell alive while Walter analyzes the sample and determines there's a repetitive DNA line that someone added on purpose. Astrid deciphers the numbers as a transposition code used by Julius Caesar that spell out three letters. One of the combinations is ZFT, which Olivia recognizes as a group connected to John Scott. Broyles notes that a biochemist, David Robert Jones, is suspected to be with ZFT and was arrested in Frankfurt by Interpol. She asks who ZFT is and Broyles notes that there have been facts relating to the Pattern she hasn't been told yet. Broyles explains that ZFT is a group of terrorists that traffic in scientific progress. Mitchell was in Frankfurt investigating Jones. Jones is in the custody of the German authorities, who have refused to give the U.S. government access. Olivia thinks she can get in to see Jones.
At the lab, Peter notes that something is in Mitchell's IV: a tendril of the parasite as it spreads through Mitchell and up the tube. Olivia calls to let them know she's heading to Germany and Peter warns that Mitchell only has a day at best.
In Frankfurt, Olivia meets with an old friend, Lucas Vogel, who now works with the German government and has connections to German Intelligence. Lucas warns that Warden Lennox of Wissenschaft Prison doesn't want to see them, so he suggests they go there anyway. Lennox doesn't want to give them access but Olivia agrees to sign everything and refuses to back down, impressing him.
Broyles visits the lab and thanks Walter for his efforts. Walter is somewhat distracted as usual and Broyles wants to discuss his behavior with Peter. Peter admits that Walter isn't focused, and that isn't going to change anytime soon. Charlie calls Broyles to inform him they've analyzed the document Mitchell brought back and each line corresponds to a FBI case file. Each one came from their office, and there's a connecting line registered to Joseph Smith. Broyles organizes a SWAT team to go after Smith.
As they wait for access, Lucas admits he's glad to be there with Olivia and he wants to be there to help her. Lennox informs them that Jones wants to see Olivia but they'll have to wait until the next morning to see him, for exactly fourteen minutes. The warden also passes on a note to Olivia. She calls Peter to tell him that Jones wants to meet with Joseph Smith. Peter drives to Smith's address to warn Broyles they need Smith alive: the SWAT team is under radio silence. Peter arrives just as the team goes in. Smith climbs out a second-story window and tries to run, drawing a gun. The SWAT team is forced to gun him down.
Peter tells Broyles that they needed Smith. Astrid calls Peter to inform him that they need help for Mitchell and have to talk to Smith right away. Peter explains that Smith is dead but the head is intact, and Walter tells Peter to bring the corpse in to the laboratory.
At the airport in Frankfurt, Lucas wonders what happened to them and invites her to stay the night. Peter calls to tell her that if Jones doesn't know Smith is dead yet, not to tell him.
At the lab, Walter discovers that Smith was shot in the head and warns that he'll have to alter the procedure due to the brain damage, and he can't guarantee results. As Walter hooks up Smith's brain, Peter realizes that Walter conducted similar experiments on him. Walter activates the circuits and they start to light up, and he explains they'll need Peter to act as Smith's ears and mouth.
Olivia accepts Lucas' offer and over wine she talks about John Scott and how he betrayed her and the FBI. Lucas admits he screwed up their relationship because he was scared and then kisses her. She hesitates and then kisses him back. They're interrupted when Peter calls to give her an update. Olivia says she'll call back from the prison but Peter notes something odd about her response. She says she's fine and hangs up, and then says she's heading back to her hotel and thanks Lucas for the meal.
As Olivia goes to the prison the next day, Walter and Astrid hook Peter up. Astrid is to ask questions and Peter will hear Smith's answers. Walter feeds current into Peter's brain but he doesn't get any answers. Olivia calls and they tell her to stall, but she only has the fourteen minutes given her. Olivia informs Jones that she'll relay questions one at a time to Smith, and provide his answers. She wonders why he didn't ask for his freedom or extradition instead of the answer to one question. He tells her that he's not responsible for Mitchell's infection.
Walter figures that Peter's own brain functions are interfering and gives him a sedative to suppress his higher brain functions. He also prepares an adrenaline shot just in case. Broyles and Samantha arrive and Broyles demands to know what's going on.
Jones suggests that the people who infected Mitchell want information from both of them and have orchestrated the whole thing to bring Olivia and Jones together. He admits he's confused as to why she hasn't started relaying his question.
Walter is ready to proceed and Astrid contacts Olivia to begin the conversation. Jones asks "Where does the gentleman live?" but Mitchell has a seizure and Astrid is forced to cut off to assist. Jones begins to wonder if they have Smith and Olivia asks why he thinks Smith would cooperate with him. Jones assures her that the people he works with are loyal and asks if she can say the same. Astrid calls back and they put the question to Smith. Peter doesn't get an answer and Walter increases the voltage without success. The guard comes to usher Olivia out and Walter tries again. Peter gets an image and draws out a series of vertical hash marks.
Olivia tries to get more time without success and Walter and Peter try to figure out the drawing. Walter realizes that the bullet destroyed the part of Smith's brain that processed horizontal lines. Peter figures out that the drawing says "Little Hill." Olivia calls it out to Jones, who gives her the antidote. She relays it to Walter who administers it to the parasite, destroying it.
Olivia talks to Lucas about Jones questioning her co-workers' loyalty. He offers to provide other sources to find out about Jones and she agrees.
Back in the U.S., Broyles talks to Mitchell and asks him about the ZFT's mole, who had higher clearance than John Scott. Mitchell says he only knows about Scott. Broyles wishes him well and as he goes, Olivia arrives. She notes they don't know who infected Mitchell and Broyles says he's proud to work with someone who won't rest until they're satisfied. Peter arrives and they watch as Samantha comforts her husband. As they leave, they're unaware that Mitchell is confirming with Samantha that their plan worked and she heard the answer: Little Hill.