This documentary does exactly what the title suggests: It provides a retrospective of the seminal rock group U2, tracing its trajectory from fledgling to mega-band status. The saga begins in Dublin, where the members of U2 -- Bono, The Edge, Larry Mullen and Adam Clayton -- first met, and follows them through the "blood, sweat and tears" years and up to the present, where the group takes its place in the pantheon of musical acts.