After her painful breakup with Joker, rapidly after the warfare with the Enchantress in Suicide Squad (2016), the already unhinged and extraordinarily unstable Harley Quinn unearths herself all on my own. But, along with her mentor out of the image and a big goal on her again, Harley locks horns with Gotham city's ruthless crime lord, Roman Sionis, who is trying to tune down a valuable diamond and the audacious pickpocket, Cassandra Cain. Now, on the hunt for the youngster road hustler and the gemstone, Quinn crosses paths with singer, Dinah Lance, Detective Renee Montoya, and a mysterious crossbow-wielding murderess who're all additionally after the lady, as Roman's pinnacle assassin, Victor Zsasz, is bent on getting Cain first. Can Harley take down the brutal exquisite-villain recognised only because the Black mask?