On May 31, 2003, Trey Anastasio played the second of two sold-out shows at San Francisco’s Warfield Theatre. On that night, Carlos Santana dropped by to say hello to Trey, ended up joining the ten-piece band on stage halfway through the first set, and continued to play with the group for the remainder of the night. The results were electric, suffused with spontaneous energy and exuberant interplay between the two guitarists.

• Music