The battle at the Booby Trap was a climactic battle between Harley Quinn, Black Canary, Cassandra Cain, Huntress and Renee Montoya at the Booby Trap against the Black Mask (Roman Sionis) and his assembled forces.
Cassandra Cain unwittingly stole the Bertinelli Diamond, an extremely valuable diamond that was the key to unlocking the fortune of the Bertinelli Crime Family, from the Black Mask's top lieutenant, Victor Zsasz. She was taken to jail for this theft and other pick-pocketing and broken out by Harley Quinn, who intended to seek the Black Mask's protection from the various individuals that were after her. Meanwhile, Renee Montoya, a detective from the Gotham City Police Department, was building a case against the Black Mask. Black Canary was a singer and a later a driver for the Black Mask Club. Finally, Huntress sought Victor Zsasz as the last remaining member of the crew that had killed her family. All of them met at the Booby Trap, where Quinn had been intending to wait to turn over Cain to him. However, when Black Mask ended up sending a small army after them, Quinn realized that they were going to have to team up in order to save both Cain and themselves.
Despite their power in numbers, the Black Mask's forces proved no match for Harley Quinn and her team. They used their various skills to easily dispatch most of the minions, variously beating them up and otherwise attacking them. Though Renee Montoya was shot in the chest by Black Mask, she survived without any significant injury thanks to the bulletproof vest that she wore. Huntress took a number of enemies using her crossbow pistol and Black Canary demonstrated her metahuman ability by using a supersonic scream to disable a number of the forces.