Mark Morris, hailed as “the most successful and influential choreographer alive, and indisputably the most musical” (New York Times) is returning to Boston with Pepperland, a unique tribute to the 50th Anniversary of The Beatles’ groundbreaking album Sgt. Pepper’s Lonely Hearts Club Band, accompanied live by an unprecedented chamber music ensemble of voice, soprano saxophone, two keyboards, theremin, and percussion. Ethan Iverson’s original score intermingles arrangements of the songs “Sgt. Pepper’s Lonely Hearts Club Band,” “With a Little Help From My Friends,” “A Day in the Life,” “When I’m Sixty-Four,” “Within You Without You,” and “Penny Lane” with six Pepper-inspired original pieces intended especially for Morris’ profound understanding of classical forms: Allegro, Scherzo, Adagio, and the blues.