With a repertoire ranging from Lady Gaga to “The Ride of the Valkyries,” The Ukulele Orchestra of Great Britain tackles an ambitious range of music—on just four strings. This group of eight genre-benders performs covers (with vocals!) of pop, jazz, country, and classics from film, along with anything else they think is ripe for the picking. Formed in 1985, the group has become something of a national institution in the UK. Since selling out the McCallum in 2016, audiences have eagerly awaited their return.