The most polished and consistent of the Portland theater companies, Portland Stage offers crisply produced shows starring local and imported equity actors in a handsome, second-story theater just off Congress Street. About a half-dozen shows are staged throughout the season, which runs from about October to May. Recent productions have included A Song at Twilight, Heroes, God of Carnage, Shakespeare’s Julius Caesar, and world premieres by playwright Tom Coash and bestselling Maine novelist Monica Wood.