Star Trek: Voyager: Season 5, Episode 15

5 - 15: Dark Frontier, Part I

Stardate: 52619.2 - After defeating a Borg scout ship, Captain Janeway decides to launch an attack on another damaged Sphere to steal a trans-warp coil (Borg propulsion technology). However, as the crew prepares for their heist, the Borg Queen is secretly aware of the entire plan. During the mission, Seven of Nine's loyalty becomes divided between the Borg and Voyager and is lured back to the Borg collective by the Queen in exchange for the crew's safety.