'Suicide Squad' director David Ayer and Margot Robbie have signed on for 'Gotham City Sirens'. Robbie is also an executive producer on the project and will reprise her role as supervillain Harley Quinn in the new movie, which will focus on the women from the DC universe. In the comic series the movie will be based on, Catwoman and Poison Ivy are featured alongside Harley and could appear in the new film. Warner Brothers is also planning a sequel to suicide squad.