Plot summary
Amanda bugs Nikita and threatens to activate the nano-cells if any attempt is made to warn Michael. After Nikita leaves Division, the rest of the team discover that she is bugged. Birkhoff jams the signal long enough for Nikita to alert Michael of her dilemma. Alex and Michael find one of the original scientists on the nano-cells project, only to be killed from the nano-cells by Phillip Jones, one of the leaders of the Shop, before an antidote can be made. Michael lies to Nikita that he has been cured.
Nikita stands down and alerts Spencer, but then sees Spencer kill herself; framing Nikita was Amanda's actual goal. To save Michael, Alex and Sonya effectively "kill" him long enough to let the nano-cells die out. Before they can revive him, Amanda sends the rest of the Dirty Thirty, now under her employ, to attack Division. As the team appear outnumbered, Nikita arrives in time, having escaped the White House, and kills the rest of them. After Michael is revived, the team leave Division and destroy it. However, the Spencer who shot herself was actually a double; the real President was captured at the G-20 summit and imprisoned. As the team work out a way to clear Nikita's name, she decides to go on the run, leaving Michael and her engagement ring behind.
Credits
Adapted from Wikipedia contributors, Nikita season 3. HTML formatting and reference markers removed.