It's Harley's birthday! She's not locked in Arkham Asylum this year, so her wish is for the most spectacular celebration ever. Problem is, her felon friends aren't available to party, and sonic songstress Black Canary keeps crashing her to-do list of fun. Will the jaunty jester's big day be a big bust or will it end on a high note? Find out in this action-packed chapter book for DC Super Hero and Super-Villain fans!