In the new series, Madsen will play Catherine Lewis, former attorney and widow of a U.S. senator from Alaska, who is determined to carry out his political legacy at any cost, according to Madsen's official website.
The show began in September and is about a government conspiracy involving extraterrestrials. The next installment will feature 12 episodes starting in the New Year.
Madsen, 49, made her acting debut in 1984 as Princess Irulan in Dune, and is well known for her part as the waitress Maya in the 2004 movie Sideways about a road trip through California's wine country.
The actress is leaving ABC's crime series Scoundrels, in which she played Cheryl West. New movies in the pipeline include Red Riding Hood and The Bell Jar.
