You can almost see and hear what Page is thinking as he adjusts a tone knob on his Les Paul between songs during Led Zeppelin's penultimate U.S. concert. While the band was onstage, Zep's manager and his personal assistant badly beat a Bill Graham Presents employee, touching off an ugly row that nearly resulted in cancellation of the next day's show at the same venue. The death of singer Robert Plant's son two days later forced the cancellation of all remaining dates on the U.S. tour, and the band never returned.