Fall Out Boy reunited for their first show since 2009 in Chicago, Illinois on Monday night (04Feb12).

The This Ain't a Scene, It's an Arm's Race hitmakers announced a hiatus following the release of their 2008 album Folie a Deux, but frontman Patrick Stump reminded fans they promised the break wouldn't be a split.

Taking the stage at the Subterranean club, the singer said, "I told you we were gonna come back! Why didn't you believe me?"

The gig came just hours after Fall Out Boy issued an unexpected press release announcing a new album, titled Save Rock N' Roll, a tour, a number of festival spots, and a last-minute string of intimate shows, which began on Monday in their native Chicago.

The band also released a new single, My Songs Know What You Did in the Dark (Light Em Up).

And the group appeared to be happy to be back onstage - Stump told the crowd, "Today is kind of a big deal for us."