Troian Bellisario has been cast in one of the lead roles of the CBS drama pilot “Ways and Means.”

It was previously announced that Patrick Dempsey would star in the series, with Amanda Warren also being part of the cast. The show centers on a powerful congressional leader (Dempsey) who has lost faith in politics who finds himself working secretly with idealistic young congresswoman Claire (Bellisario) from the opposing party to subvert the hopelessly gridlocked system he helped create. Together, they’ll attempt to save American politics, if they don’t get caught.

Claire is a newly elected, progressive, idealistic freshman Democratic Congresswoman who leads with her intelligence and straightforwardness. She’s going to have to figure out how to merge her idealism with her ambition. She will either change Congress, or Congress will change her.

Bellisario is best known for her starring role in the hit Freeform series “Pretty Little Liars,” on which she played Spencer Hastings throughout the show’s seven season run. She also recently starred in the film “Where’d You Go, Bernadette” opposite Cate Blanchett. She has also starred in the web series “Wigs,” a remake of the French cult classic “Martyrs,” and “Feed,” which she starred in, wrote, and produced.

She is repped by Gersh, Management 360, and attorney Paul Hastings.

The series hails from writers and executive producers Mike Murphy and Ed Redlich. Former CBS Entertainment head Nina Tassler will executive produce along with Denise Di Novi of PatMa Productions. Tom Lassally of 3 Arts Entertainment will also executive produce, with Dempsey executive producing in addition to starring. Phil Abraham will executive produce and direct the pilot. CBS Television Studios will produce.