As the two prepare for a gun duel, Harmonica's motive is revealed in a flashback. A younger Frank forces a boy to support his older brother on his shoulders, while his brother's neck is in a noose strung from an arch. As the boy struggles to hold his brother's weight, Frank stuffs a harmonica into the panting boy's mouth. The older brother curses Frank, and the boy (who will grow up to be Harmonica) collapses to the ground. Back in the present, Harmonica draws first and shoots Frank. He then stuffs his harmonica into the dying Frank's mouth as a reminder.