Confirmed by Warner Bros. the movie will be a Gotham Sirens movie with Harley Quinn, Poison Ivy, and Catwoman.
Catwoman, Black Canary, Batgirl, and Poison Ivy are rumored to appear in the film. All but the former will have their DC Extended Universe film debut.
Reportedly, the film will not only be a star vehicle for the Harley Quinn character but also introduce a variety of other female anti-heroes, heroes, and villains into the DC Extended Universe.
Movie will mostly focus on Harley Quinn and her origin story with appearances from Batman, Joker and some other Suicide Squad members.
The film is rumored to be based on the Harley Quinn comic book storylines Gotham Sirens and/or Birds of Prey.