Plot summary
Nikita has flashbacks of her time in Division. The Marines are sent to stop her and start shooting, so Michael, Birkhoff and Sam try to convince Nikita to back off. When Nikita kills the rest of the Group, Alex is forced to attack her from behind to save her life. After Alex, Birkhoff and Nikita are arrested, Michael and Sam decide to team up to get them out by tracking down and releasing the Group's imprisoned victims, whose doubles are under Amanda's control throughout the world. While under arrest, Nikita is visited by Amanda.
She is in full control now that all members of the Group are dead. However, Nikita is freed and imprisons Amanda, revealing that she did not kill the other members; she faked their deaths to track down Amanda. Nikita leaves Amanda locked up in the prison, where nobody can find her. Alex and Sam start a relationship, Birkhoff reveals more information about Shadownet to the public, and Michael and Nikita–who are happily married–move to Mompiche, Ecuador, and vow to keep going on missions.
Credits
Adapted from Wikipedia contributors, Nikita season 4. HTML formatting and reference markers removed.