The Foo Fighters have been dominating headlines with new music like their latest album, last year’s Medicine at Midnight (which is all sorts of brilliant), a side project disco album called Hail Satin (equally as brilliant), and a memoir from frontman Dave Grohl among other things.

With so much going on – including playing several instantly iconic live shows around the country – it’d be hard to believe that any Foo related project could be kept under wraps, so the announcement of a secret movie the group filmed and starred in came as a huge surprise when it was announced at the tail end of last year.

Directed by BJ McDonnell, the film – titled Studio 666 – follows what happens when the legendary rock band (with Grohl, Taylor Hawkins, Nate Mendel, Pat Smear, Chris Shiflett, and Rami Jaffee playing themselves) rents an Encino mansion steeped in grisly rock and roll history to record a new album. Trouble is, Grohl is creatively blocked, and when evil forces in the old house sink into his consciousness, the creative juices finally begin flowing but so too does the blood.

Studio 666 is a full fledged horror comedy, complete with tons of blood, guts and bones. Gorehounds will find no shortage of brutal mayhem throughout the film. One double chainsaw kill in particular stands out as an insane bit of horror filmmaking that’s probably the wildest bit of slasher gooeyness in quite some time - plenty of proof that nobody skimped out on the effects budget.

Inspired by the band’s actual time spent at the mansion (which they swear is truly haunted), Studio 666 seeks to bring back the fun of old fashioned band movies along the lines of The Beatles’ A Hard Day’s Night and Help!, The Monkees’ Head, and KISS Meets the Phantom of the Park. While the Foo Fighters themselves, in all their amateur acting glory, dominate the screen for most of the movie, they also bring in a handful of guests as well, including next door neighbor Samantha (Whitney Cummings) and a friendly delivery driver played by Will Forte who loves the band (well, second to Coldplay).

Of course, a film like this needs the proper music to back it up, and the Foo Fighters deliver in a somewhat unexpected, heavy as hell fashion. The band’s attempt to put together an album ends up just becoming one very long song, the start of which Grohl discovers while exploring the mansion’s basement. The song, which has been released under the band’s alter ego Dream Widow, is a certified trash metal scorcher that’s easily the heaviest thing most people have heard from the likes of the longtime rockers. The name? March of the Insane.

For those more familiar with the band’s discography and their various side projects like Grohl's metal outfit Probot, this more aggressive side of the Foos may not come as a total surprise. But March of the Insane, with its vicious sound and snarled, throaty vocals, is still the most sinister thing the group have ever put out; if anything, it's a painful tease for those wanting to hear more like it from.

In fact, it's a shame that Studio 666 only gets the one song and not at least a couple more thrash tunes to bang their head to on the way home. And with the track only coming in at three and a half minutes, it definitely makes you wonder what the full-length (and supposedly cursed) song sounds like. Last time we get a read on it, the band mentions that the song has almost become album-length itself at nearly forty minutes. So this is now an official challenge to the Foo Fighters to release the Dream Widow track in all of its full glory, so that we may indeed march to our insanity while we blast it in our homes or in our cars. We demand the entire song!

'Studio 666' is now playing in theaters.