Making a very rare appearance sans founder and director William Christie, this exceptional early-music ensemble follows conductor Paul Agnew's lead in a concert performance of Rameau's tragicomic masterpiece, Platée. Marcel Beekman sings the title role and the cast is uniformly worthy; expect serious fireworks and possible antics from Simone Kermes, routinely called the Lady Gaga of period opera but far more gifted than that label implies.