was stolen while the band were having their photo taken for a magazine in France in July 2004. It contained unfinished versions of several songs that made it onto the album. The band publicly announced that if those tracks were leaked online, they would release the album immediately via the iTunes Store. Several months later, the finished album was leaked online, but the band did not release it earlier, despite previous comments. In late 2004, "Mercy", an unreleased track taken from the How to Dismantle an Atomic Bomb sessions, surfaced on the Internet through a fan who had been given a copy of the album containing the extra track. The track is of less than standard audio quality, but managed to become a favorite on fan websites. It was cut from the final release, but was described by Blender as "a six-and-a-half-minute outpouring of U2 at its most uninhibitedly U2-ish". The lyrics to the song can be found in the booklet for the Special Limited Edition. A significantly revised version of the song was performed during the European leg of the U2 360° Tour; it made its live debut on 12 September 2010 during the second Zurich concert, and was officially released as the opening track on the band's Wide Awake in Europe vinyl-only live EP that November. Composition As with All That You Can't Leave Behind, this album finds U2 returning to "more 'stripped down' rock and pop sounds", according to musicologist Susan Fast. Adam Clayton said of Atomic Bomb, "It's very much a guitar record. "Vertigo", "Love and Peace", "City of Blinding Lights", "All Because of You", all pretty up, rocky tunes. A lot of them are a kick-back to our very early days, so it's like with each year we have gathered a little bit more and this is what we are now." In 2003, Bono said one of their new songs called "Full Metal Jacket" was "the mother of all rock songs" and "the reason to make a new album". A similar demo called "Native Son" was also recorded. Both of these demos would later become "Vertigo". Contemporary Christian artist Michael W. Smith joined the band in the studio during the Atomic Bomb sessions and worked on at least one track with them, entitled "North Star". That track, which was a tribute to Johnny Cash, has not yet surfaced officially or unofficially in any form. A