Complex sentence: In "The Breakout", Black Mask steals a powerful shock-wave generator and holds Gotham City hostage, but he is defeated by Batgirl and Robin while Batman deactivates his device.
Split into simpler sentences: In "The Breakout", Black Mask steals a powerful shock-wave generator and holds Gotham City hostage. He is ultimately defeated by Batgirl and Robin, while Batman deactivates his device.