Desperate for one last chance at the fame and notoriety they never achieved, a down-and-out rock band tries to reinvent itself through appropriating Satanic imagery, and accidentally summons an ambitious lesser demon hell-bent on taking over the band...and the world.

SYNOPSIS:

The rock band Filth (Dirk, Les, Bobby, and Slim) was going to take the world by storm – they had a couple moderately-successful singles on their debut album and everything was looking up. Five years and a dud sophomore album later, they've been reduced to playing the county fair circuit, desperate to keep their name alive in the hearts of the fans they have left. But when they're upstaged by a truck and tractor pull, the band has finally had it – they convince themselves they need to go back into the studio and somehow recapture the “magic” of the first album and get back to playing the big venues in front of big crowds of adoring fans.

When they meet with the label about a new album they find out not only has their manager dropped them behind their back, but their manager never mentioned the label also had dropped them. With the band unsure what to do next, Dirk takes it upon himself to reinvent the band's image using “Satanic theater” to attract more attention to themselves. Trying to be authentic, Dirk surprises the rest of the guys by performing a ritual from “The Devil's Bible” during rehearsal, and accidentally summons a demon named Gaahl, who's excited to be part of a rock band, and convinces the guys to let him help them with their “Satanic rebranding” as their new manager and part of their stage show.

The addition of Gaahl reinvigorates the band, under the name Sinistaar, and they start building a whole new fanbase from all the attention Gaahl has brought them. But as their success builds, Gaahl pushes for more and more of an active role in the band, namely as lead singer. There is less and less room for both Dirk and Gaahl in the same band, and Gaahl eventually manipulates the others to kick Dirk out.

With his tail between his legs, Dirk goes back home to Idaho, seeking advice from their local Mormon church on exorcising demons. Instead, he finds himself unexpectedly reconnecting with the church community and finding true joy playing in the church band. But when Dirk sees Sinistaar on the cover of a magazine without him, he's overcome by jealousy and convinces his new church bandmates to run off with him back to Los Angeles to become Christian rock stars. Their new band Houndstooth quickly takes off, and quickly even surpasses Sinistaar's level of success.

Meanwhile, Gaahl has taken further control over the band by amassing a growing mob of cult-like followers and spending the band's money on a sprawling desert compound, where he plans to get the label to build their own recording studio, in order to further his ultimate goal – elevate himself as the Anti-Christ and bring about Armageddon.

Meeting with the label, Sinistaar find out they are being dropped, now that Satanic bands have become less fashionable than more wholesome Christian rock bands, like Houndstooth, who happen to meet with the label immediately after them to receive their first gold record. Enraged, Gaahl murders Dirk's bandmates, but Dirk manages to barely escape. Not wanting to be pawns in Gaahl's plan any longer, the rest of Sinistaar secretly seek help to banish Gaahl from the Los Angeles Archdiocese, where they find Dirk hiding out.

Armed with a special demon-killing artifact on loan from the Archdiocese, Dirk infiltrates the desert compound during huge “Armageddon kick-off” show, sneaks on-stage, and dispatches Gaahl while the band is playing, in front of thousands of Gaahl's followers. The angry horde destroys the stage, out for blood, and the guys huddle up and hold them off best they can. Right before they are overrun, a Vatican attack helicopter swoops in and saves them, but not before Slim is pulled into the crowd to his death. The remaining members of Sinistaar fly off, never to speak of this or see each other again.

Bobby lived the rest of his life as a humble auto mechanic. Les led a short, violent reign of terror against the record industry before going to prison. Still trapped by blind ambition, Dirk performs country music...at the Idaho mall food court every Tuesday, next to the Orange Julius.

SINISTAAR!