Roulette had Stephanie's would be date, Francisco Gracia kidnapped by armed thugs. Stephanie attempted to defend him, but got grazed in the head by a bullet.
Francisco's father allowed his son to be kidnapped as a way to repay his gambling debt. The intent of the kidnapping was so Francisco could be used as bait to lure Batman into Devil's Square so that the villian team Roulette had gotten together- Roxy Rocket, Riot and Dr. Phosphorus- could take Batman out while Roulette booked bets on the outcome. It worked. Now it was up to Steph and Damian to save Batman!
Save them they did- Stephanie defeated Roxy and Dr. Phosphorus in one go by hijacking Roxy's rocket and crashing it into Phosphorus- with Roxy on it! Steph then helped Damian defeat Riot. Roulette decided to leave, but by then, Oracle had hacked into her systems and Batman, Robin, and Batgirl were there to cut off her escape. Damian quipped, "Game over," and Steph chastised him, "Don't be lame." Dick said, "Shh, he's learning". So the three took Roulette in.
Find out more about Roulette here.