Emmy Rossum to star in Showtime pilot

Allison Janney, Justin Chatwin also land roles in 'Shameless'

Emmy Rossum is set as the lead opposite William H. Macy in "Shameless," John Wells' drama pilot for Showtime.

Additionally, Allison Janney has signed on for a key recurring role, reuniting with her "West Wing" executive producer Wells. And Justin Chatwin has been cast in the pilot from Warner Bros. TV/John Wells Prods.

Based on the long-running British series by top U.K. TV writer Paul Abbott, "Shameless" revolves around the Gallaghers, a working-class Chicago clan dealing with the recession. The mother is AWOL, and the alcoholic patriarch (Macy) usually ends up passed out on the living room floor, so their smart but unpredictable 18-year-old daughter Fiona (Rossum) is tasked with keeping her five younger brothers and sisters on the straight and narrow.

Janney plays a pivotal character that will become a love interest for Macy.

Chatwin will play Steve, a car thief who falls in love with Fiona.

Mark Mylod is directing the pilot from a script by Abbott and Wells.

Rossum's breakthrough came in 2004 when she starred in "The Day After Tomorrow" and "The Phantom of the Opera"; the latter earned her a Golden Globe nomination.

She most recently starred opposite Chatwin in "Dragonball: Evolution." Rossum is repped by ICM and BenderSpink. Chatwin, repped by UTA and Alchemy, also co-starred in "War of the Worlds."

Janney, who won four Emmys for her supporting role on "Wing," worked with Showtime entertainment president Robert Greenblatt for the past two years on the Broadway production of "9 to 5," which she headlined and he produced. Janney is repped by Paradigm and Thruline.