Star Trek: Voyager: Season 6, Episode 2

6 - 2: Survival Instinct

Stardate: 53049.2 - Seven of Nine discovers that she was freed from the Borg collective once before with three other Borg drones when their ship crashed on a planet. She is also responsible for their re-assimilation. Now, the three renegade drones stalk Seven because they are linked in their own "collective" and want to learn from Seven how to terminate their neural links and restore their individuality. Seven is willing to help.