(CNN) In "Suicide Squad," Margot Robbie's Harley Quinn was the best part of a bad movie. That's true again with "Birds of Prey," which moves the Joker's sadistic sidekick front and center, then proceeds to assault the senses in much the way its protagonist wields a baseball bat.

The too-cute subtitle, "And the Fantabulous Emancipation of One Harley Quinn," underlines the cheeky tone to which the film aspires and doesn't fully sustain. Part of that has to do with jumping around as it juggles an assortment of characters, finally bringing them together in what feels like a belated bid for a sequel.

As for the "emancipation" part, the movie begins with the lovelorn Harley recounting her history via an animated sequence, explaining how she met the Joker (or "Mr. J," as she prefers), fell for him and became his main squeeze.

A bad breakup has left Harley alone and exposed, with plenty of people bearing grudges (or "grievances," which flash across the screen) and eager to exact a measure of revenge.

Harley, however, isn't Gotham's only violent psychopath. In fact, she looks positively reasonable compared to many of the town's denizens, including Roman Sionis (Ewan McGregor), a ruthless crime boss whose right-hand henchman, Victor Zsasz (Chris Messina), derives pleasure from peeling off victims' faces.

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