Helen Mirren and Ryan Phillippe are teaming to star as a mother-stepson gangster team in Lee Daniels' indie film "Shadowboxer." Shooting is scheduled to start April 1 in Philadelphia, with Daniels making his directorial debut from a script by "Monster's Ball" co-scribe Will Rokos. Mirren is in talks for the project, with Phillippe in negotiations for the lead male role, according to their reps. "Shadowboxer" centers on the unusual relationship between a mother (Mirren) and her stepson (Phillippe). The duo, who have a romantic relationship, work as contract killers. Wes Bentley is attached to play the lead villain on the hunt for the killer couple. For the pic, Daniels has recruited famed fashion designer Vivienne Westwood to make her feature film debut as the project's stylist. Mirren is repped by ICM. She stars in the December release "Calendar Girls" opposite Julie Walters for Touchstone Pictures and helmer Nigel Cole. She next stars in "The Clearing" for Fox Searchlight Pictures and "Raising Helen" for Buena Vista Pictures. Phillippe is in front of the cameras on the ensemble drama "Crash" for helmer Paul Haggis, Stratus Film Co. and Bull's Eye Entertainment. He is repped by UTA.