Joan Cusack Joan Cusack

Joan Cusack has joined Showtime's upcoming drama Shameless, the network announced Tuesday.

Based on a British series, the John Wells-produced show revolves around Frank Gallagher (William H. Macy), the alcoholic patriarch of a Chicago family.

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Cusack will play Sheila, an agoraphobic housewife with a sexually active teenage daughter who befriends Frank. Allison Janney was originally cast in the role, but she left the series for ABC's midseason comedy Mr. Sunshine.Shameless, which also stars Emmy Rossum, premieres Sunday, Jan. 9 at 10/9c.