Nikita and Michael plot to take down Division and Oversight and are prepared to use the contents of the black box to do so. Amanda is now running Division but Oversight has assigned one of their own, a new agent named Sean, to keep an eye on her.
Nikita and Michael investigate an old corrupt Division program called P9 that appears to have resurfaced. During their investigation, they run into Owen, who informs them that he is searching for Dr. Joseph Mars, the man who not only masterminded P9, but also invented the Regimen and could help Owen wean himself off the dangerous drug.
Birkoff tells Nikita and Michael that a black box file reveals that an international terrorist named Ramon, who has been taking credit for some serious political assassinations, now works for Division. This news upsets Nikita since she was the agent that captured Ramon years ago and turned him over to Percy. Amanda convinces Alex to hug Anton Kochenko, a man who used to work for Alex's father.
Nikita is stunned when she hears that her old Division partner Kelly escaped from a Turkish prison. Nikita thought Kelly died years ago and always felt responsible because it happened on the mission where Nikita escaped from Division.
Michael discovers Cassandra, a woman he once romanced under Division orders, is in danger. Feeling guilty for how things ended, he wants to help her but Nikita suspects there is more to it than easing his conscience. Amanda manipulates Alex into helping her on a mission but Sean gets caught in Amanda's web of lies and begins to doubt Division's true motives.
While searching for information on the black box, Birkoff stumbles upon Nikita's birth certificate. Nikita and Michael track down Nikita's father Richard, but the reunion is not quite what Nikita expected. Percy tells Alex that the black box that Nikita has contains information that could help her avenge her father's death.
From behind bars, Ryan uncovers patterns that reveal how Oversight gets its funding. He sets up a meeting with Nikita to fill her in on the details, but Amanda intercepts their coded messages and alerts Oversight, who sends in one of their members own to question Ryan.
Michael becomes concerned when he learns that Cassandrais in trouble, and he rushes off to protect her. Michael discovers that General Tupelovhas accused her of stealing two million dollars and has threatened to hug her unless she returns the money.
Nikita steals funds from Oversight, forcing them to host an emergency meeting. Nikita and Birkoff figure out how to spy on the meeting so Nikita can identify the other members of Oversight, but things go awry and Sean captures Birkoff.
With Michael out of town, Nikita turns to Owen to help her track down and steal another black box from a Guardian. Unfortunately, she discovers that Owen is working for an unlikely employer that could jeopardize Nikita\'s whole operation.
Alex's mission to bring down Gogol comes to a head when she infiltrates her childhood home and faces ghosts from her past. Nikita, working on a separate mission, finds herself at the mansion as she tries to steal Semak's black box. When Nikita and Alex cross paths, they decide to team up, but the pair faces a major obstacle.
Sean attacks Nikita and Michael in an effort to protect his mother. Meanwhile, Percy gets the upper hand on Amanda and threatens to level Division unless she releases him.
Percy has his Guardians hold the members of Oversight hostage until Amanda agrees to his demands. If she doesn't, the Guardians will shoot all the members of Oversight and release a deadly gas inside Division that will instantly hug everyone, including Amanda. Nikita is torn between letting the enemy fall and saving the innocent lives inside Division. Meanwhile, Sean is frantic to save his mother from Percy's clutches and turns to Nikita, Michael and Alex for help.
Percy continues his plan to take back Division by threatening to hug Nikita's mentor Carla, the woman who took Nikita off the streets when she was a junkie. Determined to get to Carla before Percy, Nikita uses Madeline to send her a message. Percy intercepts the message and it's a race to see who can get to Carla first. Meanwhile, Amanda tells Alex it's time for her to take back Zetrov and reveal to the world that Alexandra Udinov is alive.
Nikita and Michael try to help Carla remember her past, which holds the key to taking down Division. Carla recounts the night Nikita was arrested and Nikita is stunned at what she learns. Meanwhile, Alex shows up at a Zetrov press conference where Semak is speaking and announces that she's Alexandra Udinov. Alex demands a trade - her mother for the empire.
Division is in an uproar when their agents are being assassinated one by one. Amanda realizes Percy is behind the murders and is trying to undermine her authority with the other Division agents. She reluctantly calls Nikita with an offer that is hard to resist - stop Percy and she'll give Nikita Ryan.
Michael is furious when he discovers a secret that Cassandra kept from him, so he and Nikita fly to Moscow to confront her. Meanwhile, Alex makes a last ditch effort to find her mother by sending out a coded message through a televised interview.
Amanda and Ari set up a board meeting with Zetrov and prepare to take over the company. After a heated face-to-face confrontation between Nikita and Amanda, Nikita recalls what Amanda was like when she was first brought to Division. Meanwhile, Alex surprises Ari by showing up at the board meeting with an old and powerful friend.
When Nikita worked for Division, she targeted a man named Nicholas Brandt and infiltrated his inner circle. She captured him and he's been behind bars ever since. However, Percy springs Brant, and his first mission is to capture Nikita for payback. After he has her in his clutches, he tortures her, forcing Nikita to face a side of herself she thought she had long buried. Meanwhile, Percy continues to play mind games with Michael, Alex and Sean, pushing one of them to the brink of death.
Nikita convinces a reluctant Birkhoff to use 20 million dollars of his own money in a plan to bankrupt Percy and Division, but when Percy ends up stealing Birkhoff's entire life savings, Birkhoff and Nikita clash. Team Nikita has one last chance to hit Percy again, but Birkhoff is arrested trying to regain his millions and Nikita realizes she must break him out of jail before Division gets to him. Michael and Alex go after Birkhoff's stolen money while Nikita goes to save Birkhoff.
When it looks like Percy's nuclear weapons plan is getting out of control, Ryan suggests they go to the Director of the CIA, Morgan Kendrick, for help. Nikita is vehemently opposed to the plan and is surprised when Michael takes Ryan's side. Tensions escalate when Nikita is proven right after they discover Kendrick has a link to Percy. Meanwhile, Sean is shot by Percy's men, shaking Alex to the core.
Percy calls the President the United States and threatens to set off a nuclear explosion unless his demands are met. Birkhoff finds two scientists who could help stop Percy's new nuclear satellite, so Nikita and Michael head after one and Sean and Alex look for the other. Unfortunately, Alex and Sean get caught at the very location that Percy blows up as an example of his power. Meanwhile, Nikita realizes the best way to stop Percy is to go into the belly of the beast - Division itself.
Nikita and Michael invade Division in an attempt to capture Percy. Alex and Sean get caught in a deadly gunfire battle with the U.S. Marines and Ryan must convince the President of the United States not to destroy Division until he is sure Nikita and Michael are safely out of the building, but the President is eager to end Percy's reign. Meanwhile, Birkhoff asks Sonya for help, and Nikita corners Percy in his office, but he pulls out one final trick that may cost her the battle.