Spinning out of the runaway hit Batman: Beyond the White Knight comes an unforgettable coming-of-age super villain tale starring the children of Harley Quinn and The Joker! When the rebellious twins run away in a stolen Batmobile, only Joker Jack Napier's quickly fading hologram has any hope of getting them home safely and keeping them out of the family business. But a life of crime isn't the only temptation they are facing: the kids uncover a dark secret that could bring their dad back to life for good!