The Borg are changed and Data is tempted by emotion.
The Borg attack a Federation outpost, but these drones behave as individuals and talk to their victims. While fighting one, Data feels anger for the first time, and later pleasure at having killed. He also uses the holodeck to play poker with images of famous scientists.
The Enterprise finds a group of renegade Borg, and Data leaves with one of them, Crosis. Picard takes an away team to a planet to look for him. They find Data among the Borg, who are now led by Lore, his brother, and Data announces that he is on Lore's side.