This is the lead single from Icelandic post-rock band Sigur Rós' seventh album, Kveiku. The song title is Icelandic for 'Brimstone'. It was first performed live in November 2012, during the Iceland Airwaves 2012 music festival, where they were the headlining act. It was released as the lead single from the album on March 25, 2013.
A goth-tinged video was released to accompany the song. Directed by Andrew Huang, who has also worked with Björk, it features the group performing in an ashen waste of black. The clip cuts back and forth between the shots of the band and a narrative sequence which depicts the capture of a prisoner, his escape and chase.