The trio of productions includes “Barrymore,” “The Belle of Amherst” and “Barefoot in the Park.” The shows are ALT’s first to be produced live on stage in 15 months. “We’re doing small cast shows for summer,” executive director Henry Avery said. “Audience response has been incredible.” ................................................................ Christopher Plummer won a Tony Award for his portrayal of John Barrymore in the acclaimed Broadway production of “Barrymore.” ALT’s Mario Cabrera (of “Amadeus”) plays the title role. The play opens with Barrymore down on his luck and in rehearsals for a revival of “Richard III.” “He was an alcoholic and had a lot of personal issues,” Avery said. “Growing up in a theatrical family – it was a hard life to live up to those expectations.”