"Harley Quinn loves fighting crime with her classmates like Wonder Woman, Batgirl, and Supergirl, but she always does it her with own madcap style--and a big mallet! It's no surprise that Harley can't resist getting involved with an upcoming inter-school battle of the bands and a fantastic cosmic carnival that appears only once a year--and this year, it's coming to Earth! But as things get stranger, Harley knows how to get to the bottom of a mystery--and...

When Dr. Harleen Quinzel, a psychologist at Arkham Asylum, falls in love with love The Joker, she transforms herself into Harley Quinn, the Clown Princess of Crime, friend of Poison Ivy, enemy of Batman, and a super villain in her own right.

With the financial help of Lex Luther, the Joker and Harley Quinn plan to trap the Justice League in a "jail" beneath Arkham Asylum, using Flash and the Huntress as bait--and Batman, Wonder Woman, and the rest of the heroes must rescue their friends, while avoiding the traps the Joker has set.

Harley Quinn and Poison Ivy escape from Arkham Asylum and head back to Ivy's hideout; however, Harley proves to be a demanding roommate, so Ivy helps her take over a carnival and even grows her plant versions of Batman and Robin to boss around--but when Poison Ivy feels she has done enough and withdraws from the field, Harley discovers that being a criminal boss is a lot more difficult than she imagined.

"When Harleen Quinzel scores an internship in a psych lab at Gotham University, she's desperate to make a big discovery that will land her a college scholarship and help her escape her abusive father. But when Harleen witnesses how women are treated--and experiences harassment herself--she decides that revenge is more important than her own dreams. Harleen finds her place in the Reckoning, an intoxicating girl gang whose members create chaos to inspire...

There is a big Halloween Party at the Gotham City Museum, and Harley Quinn sees the party as an opportunity to steal some of the Museum's treasures--and it is up to Batman and Nightwing to prevent her from unleashing chaos on the innocent party guests.

Harley Quinn appointed herself the Joker's assistant, but when he humiliates her and takes her two hyenas, Harley is determined to get them back and get revenge as well--by leading Batman and Robin to the Joker's secret hideout.

Explains the back story of Harley Quinn, a psychiatrist at Arkham Asylum who became obsessed with the Joker and turned into his demented sidekick to battle against Batman and Robin.