Bruce Geller conceived and initially produced Mission: Impossible, an American television series. It details the missions of a group of secret government spies known as the Impossible Missions Force. Dan Briggs, portrayed by Steven Hill, is the squad's leader in the first season; Jim Phelps, portrayed by Peter Graves, leads the team in subsequent seasons. Lalo Schifrin composed the theme music for the series. The sitcom aired on CBS from September 1966 to March 1973, and then reappeared for two seasons on ABC from 1988 to 1990, with only Graves remaining in the cast. Later, beginning in 1996, it served as the basis for a popular film series starring Tom Cruise.