The fifth single from Metallica's ninth studio album, 'All Nightmare Long' might be one of the heaviest tunes churned out by the band in recent memory. As the epitome of what 'Death Magnetic' stands for as an album,' 'All Nightmare Long' features killer guitar riffs, speedy rhythms and face-melting solos. It's considered the best song on the album by many critics and fans.

In a 2008 interview, James Hetfield said of 'Death Magnetic,' "It's a look backward ... taking the essence of our earlier style and playing it with our current skills." If there is one song on the album that lives up to that description, 'All Nightmare Long' is it. Interestingly, the guitar riffs were not only developed by the two axemen, Hetfield and Kirk Hammett, but also by bassist Robert Trujillo. In the making-of documentary of the album, the song was first referred to as 'Flamingo' because of the type of guitar Trujillo used when messing around (a flamenco guitar) during practice. As Hammett and Hetfield watch Trujillo bust out undeniably complex riffs, Hammett leans over to the lead singer and says, "Maybe you and I should just quit."

As the song took shape in the studio, a name was needed. Cliff Burnstein, co-founder of Q-Prime Management, suggested the title 'Hunt You Down Without Mercy.' Lars Ulrich, being the vocal band member that he is, spoke up and said, "My title is 'All Nightmare Long' ...  it's such a clever twist on all night long." With that, the song had an official name.

Inspired by a short story called 'The Hounds of Tindalos,' Hetfield says the lyrics are "about these wolves that hunt through their nightmares." Apparently, as the singer explains, the only way to get away from the wolves is to "stay with angels. You can't even escape through sleep." It only makes sense that a song as crushing and brutal as 'All Nightmare Long' would be based on a story that is equally terrifying as it is mythical.

The song, along with all others on 'Death Magnetic,' gives writing credit to all four members of Metallica. First played live on Dec. 5, 2008 in Calgary, Canada, nearly three months after 'Death Magnetic' was released, 'All Nightmare Long' has been played over 100 times to date. It is the third longest track on the album, clocking in at seven minutes and 58 seconds. The music video is a frightening mockumentary created by Robert Schober, aka Roboshobo, and does not feature any member of the band. It is easily one of the strangest music videos released by Metallica.

Watch Metallica Perform 'All Nightmare Long' - Calgary, Canada - Dec. 5, 2008

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