A murder scene with a bloody bat symbol spells trouble for the Batman. Thanks to Hattie Tetch's smear campaign, the Dark Knight detective faces more public scrutiny than ever before. Determined to clear his name, the Batman discovers a fanatical bat cult led by a charismatic prophet, the Mad Monk. 

A series of mysterious student deaths at Gotham University draws Harley Quinn out of hiding. When her investigation converges with the Batman's, the two former adversaries strike an alliance to take down the immediate threat- the Scarecrow!