Three Years Ago
Olivia tends to Mark's shoulder wounded after he's shot during a FBI case. She wonders if she can handle the stress. When Mark notes that she knew what she was getting into when they married, Olivia notes that now they have a daughter, and something needs to change. Mark tells her that he's been offered a surveillance position on a counter-terrorism unit. Olivia figures that he'll hate it, but Mark wants to take it so he'll be there for his family and that they'll always come first.
After their argument about his priorities, Mark moves out of the house to live with Stan and his wife. As he goes, Charlie waits for him in the car. He gets in and admits that he's going away for awhile, but he's not abandoning her. Charlie gives him the friendship bracelet she made for him and Mark hugs her.
Mark and Stan watch the Dyson Frost tape that Demetri and the others brought back from Somalia. Frost talks to Demetri, ten years in the future, and explains that he had a flashforward that let him see that he would engineer a successful worldwide Blackout in 2009. On the tape, Frost also talks about how he evaded them in Pigeon, UT, and that he's had hundreds of flashforwards. In almost all of them, he dies with Demetri on March 15, 2010. He tells Mark that the next move is his. Mark and Stan finally tell Demetri that they've learned that there will be another Blackout, and Stan tells them to stop it.
Simon and Lloyd examine the equipment and files taken from the remaining tower in Somalia, and Simon realizes they're based on sketches he did when he was 13. There are also references to tachyonic dark matter, which wasn't known to exit in 1991. Simon is relieved that this proves that they had nothing to do with the Blackout, and Frost and his people used flashforwards to steal their technology. However, Lloyd points out that they still bear some responsibility since it was their experiment that was used to amplify the Blackout effects. Among the files, Lloyd notices the formula from his flashforward and realizes that it demonstrates a way to protect against the effects of the Blackout. Simon suggests that Lloyd talk with Olivia to see if she remembers the full formula.
Demetri tries to track Frost and discovers that there's been no sign of him since his fake death in 1990. Mark follows up on Frost's interest in chess and discovers that the scientist beat the reigning champion, Ian McKinnon, using a Queen Sacrifice. McKinnon lives in San Francisco and has refused Mark's calls. They look at Frost's winning game against McKinnon and discover that the timing of his chess moves spell out a phone number in Morse code. When they dial the number, they get Frost's pre-recorded message congratulating them and saying that it's Mark's move.
Keiko, out of work on low on cash, waits at the sushi restaurant for Bryce to show up. The waitress, Hitomi, suggests that Keiko take a job as a waitress, but Keiko wants to start a new life for herself.
Bryce is receiving chemo treatment at the hospital when Nicole comes to see him. He isn't happy to have there seeing him at a moment of weakness, but she notes that she's already seen him with her lunatic mother. Nicole invites him out to dinner so he can have fun before the chemo side effects kick in, and Bryce agrees as long as he pays.
As they look for McKinnon, Mark and Demetri are called to the scene of a murder: an outdoor chess park. The SFPD detective informs them that McKinnon is dead.
That night, Mark meets with Vogel. They figure that the mole tipped off Frost that McKinnon was under investigation and had the loose end eliminated. The two agents decide it's time to reveal the mole, although Mark warns it'll become ugly.
The next day, Vogel brings in a team of FBI sweepers and orders Stan and all of his people into a conference room while the sweepers check the computers and phones for bugs. Vogel informs the angry Stan that he's not at large to provide an explanation. Simon is also brought in, and they realize what is going on. They notice that Mark isn't with them, and Stan explains that Vogel already vetted him. Mark meets with Vogel and the sweeper finds nothing until Vogel starts singing. That activates a voice-trigged transmitter hidden in Mark's keyboard and they quickly track the signal. Vogel says it's time to begin.
Vogel goes to the conference room and informs them that they're looking for the mole. He takes Demetri outside for interrogation, but Mark explains that they don't suspect him. However, they had to make it look convincing to fool the mole.
In the conference room, tempers start to flare. Agent Curdy nervously admits that he has computer RPG materials stored on his work computer, and he and Simon discuss online gaming. Mark comes in and shows them the transmitter, disguised as an "M" key, and Simon half-seriously suggests that Marcie Is the mole. As she gets a cup of coffee with no sugar, she tells mark that they're all there for him.
As Keiko walks down the street, she notices some local teens dancing and rigging their cars to bounce. She notices one of them, Emil Gutierrez, trying to rig his car. She offers her mechanical expertise and once he's convinced she's serious, Emil accepts.
Mark and Vogel interrogate Janis and confront her with their knowledge that she's taken a large number of personal days. When she tries to claim they're for fertility clinic visits, they note that the number of days and scheduled visits don't match up. Janis admits that she was conducting her own investigation. She checked on Marcie and learned that she had an undeclared half-brother with a debilitating illness. Someone anonymously deposited $50,000 into Marcie's account to cover the expenses. As Janis leaves, she worries that she's not doing the right thing.
Olivia and Charlie go to the amusement park on the pier. Charlie wants Mark there and Olivia assures her that they'll always be together. As they ride the Ferris wheel, a man watches them from another gondola.
Demetri checks up on Marcie and confirms that she has a half-brother. However, she did declare him on her FBI application and the paperwork was sent to the wrong place. Which means that Janis legitimately could have missed the information. Mark finally admits to Demetri that he's moved out of his house and Demetri offers his help, but Mark admits there's nothing he can do and tells him to continue the investigation.
As they ride on the merry-go-round, Olivia notices the man who is following them. She tries to run with Charlie but the man cuts them off... and introduces himself as a FBI agent assigned to her security detail by Mark.
Emil takes Keiko to his garage and offers her a job. When one of the mechanics suggests she's sleeping with her new boss, Emil tells him to shut up and warns everyone to treat Keiko like one of the family. They all quickly agree.
At the hospital, Olivia is leaving a message for Mark thanking her for the security detail when Lloyd comes in. He asks what she remembers and she reluctantly describes her flashforward in bed with him, and how afterward she saw the formula. She remembers that part of it is the chemical formula for halothane, an anesthetic, and Lloyd realizes that he was working on a quantum entanglement device. He apologizes for involving her but Olivia says that she understands.
Keiko and Emil go to the sushi restaurant and she explains about her flashforward, and how it was the first time that she was happy because she followed her heart. Emil refuses to tell her what he saw in his flashforward, and says only that it was something different than her's. Keiko thanks him for the job and they share a drink.
Bryce and Nicole walk through Little Tokyo and talk about his flashforward. As they look at the menu posted outside a sushi restaurant, he suddenly kisses her. He quickly backs away and apologizes, and Nicole, shocked, rallies and says that he must have been thinking of Keiko. They decide to go for burgers, unaware that Keiko is inside.
The next day, Keiko and Emil are working at the garage. ICE agents break in and raid the place, and arrest Emil for employing undocumented workers. They arrest Keiko as well and haul her away in a van.
Bryce is driving to work and calling Nicole to apologize. He stops at a light and watches the ICE van drive by, unaware of whom is inside.
Demetri and Mark go through surveillance footage and Demetri notices shots of Marcie outside by the fountain drinking coffee. When Mark notices that she puts sugar in her coffee, he remembers that she said in the conference that she doesn't take sugar. He matches the times when she uses sugar outside with the incidents when the mole gave away information, and realizes that she's signaling her handlers.
In the conference room, Marcie sees Mark and Demetri looking at her and starting to draw their guns. She grabs a gun and opens fire, shooting Curdy and several others. She runs down the stairs and outside to where a waiting motorcyclist picks her up before Demetri and Mark can stop her. However, Janis cuts her off and shoots the motorcyclist. The bike goes into the fountain and Janis knocks out Marcie and hauls her onto dry land. Mark admits that Janis was right about Marcie, and she wishes that she wasn't.
Back inside, Mark talks to Stan and admits that he was under orders not to bring Stan into the loop. Stan notes that Mark used a Queen Sacrifice, just like Dyson. When Mark wonders how he heard about that, Stan just smiles and says that he has his sources. As Mark walks away, he gets a call from Frost. The scientist says that he's satisfied that Mark can keep his leads alive and promises that they'll soon meet in person.
That night, Janis and Simon leave through the parking garage, and Simon flirts with her. Janis comments that the x-rays show that Simon murdered Flosso, and figures that he was trying to send a message. She tells Simon that she's got the message, and he realizes that she's the second mole. With Marcie dead, Janis can now operate freely with no one the wiser.