Metallica and Lou Reed have combined forces for a new collaborative effort, due on Halloween. The two artists have announced "Lulu," their first combined effort, and revealed details on the concept recording.

Loureedmetallica.com launched late last week with just a photo on its front page, but now a post, more photos, a gradually growing tracklist and more have shown up over the weekend. A long post explains the inspiration:

"Lulu" was inspired by German expressionist writer Frank Wededkind's plays "Earth Spirit" and "Pandora's Box," which tell a story of a young abused dancer's life and relationships and are now collectively known as the "Lulu Plays." Since their publication in the early 1900's, the plays have been the inspiration for a silent film ("Pandora's Box," 1929), an opera, and countless other creative endeavors. Originally the lyrics and musical landscape were sketched out by Lou for a theatrical production in Berlin, but after coming together with the 'Tallica boys for the Rock and Roll Hall of Fame concerts in New York in 2009 all guilty parties knew they wanted to make more music together. Lou was inspired enough by that performance to recently ask the band to join him in taking his theatrical "Lulu" piece to the next level and so starting in early May of this year we were all camped out recording at HQ studios in Northern California, bringing us to today and ten complete songs.

The coming-together began "a few months ago," and Rolling Stone reported the potential for the record back in June.

"Lulu" will be out on Oct. 31. Metallica last released "Death Magnetic" in 2008. The former Velvet Underground frontman previously dropped "Lou Reed's Inner Spaces" in 2007.