Complex sentence: His roommate Sam Simpson (Valerie Perrine), a supermodel newly retired at the peak of her success, sees the response to a song he wrote for her ("Samantha") and agrees to use her connections to get him a record deal.
Split into simpler sentences: His roommate Samantha "Sam" Simpson (Valerie Perrine) is a supermodel newly retired at the peak of her success. She sees the response to a song he wrote for her ("Samantha") and agrees to use her connections to get him a record deal.