When the British prodigy George Benjamin was 16, the grand panjandrum Olivier Messiaen likened him to Mozart, thinking no doubt of the youngster’s technical precocity. But unlike Mozart, Benjamin turned out to be a very slow worker. When Mozart died at age 35, he had—besides vast quantities of instrumental and sacred music in all genres—a whole catalog of immortal operatic masterpieces to his credit. Benjamin was into his forties before he first dipped a toe into opera, producing a memorable miniature. The cast list for Into the Hill names four characters, a narrator, and The Crowd, yet Benjamin makes do with just two voices, both female, accompanied by a chamber ensemble of roughly a dozen, and gets you in and out of your seat in a swift 40 minutes. The subject is the Pied Piper, scarily rewritten for grownups, with nary a trace of whimsy. —M.G.