Since the Big Boom of countertenors back in the 1980s and 90s, many a contender has come and gone. Bejun Mehta, among the first to break out, still stands as one of the most captivating, and in Orlando, he has one of Handel’s richest roles, complete with a mad scene in rather strange meter. The production by the Haymarket Opera Company premieres over three evenings, one act at a time, each with its own virtual opening-night party. The opera will stream in its entirety throughout October. One admission buys access to the whole package. The company name, be it noted, alludes to Chicago’s Haymarket Affair of 1886, a milestone in the international struggle for workers’ rights, and also to the Haymarket district of London, home to the King’s Theatre, where Handel produced his Italian operas. —M.G.