Icelandic post-rock band Sigur Rós has released a haunting version of Game of Thrones' "The Rains of Castamere." The band isn't the first guitar group to cover songs from George R. R. Martin's fantasy lands of Westeros and Essos, but where indie rock outfit The Hold Steady was chosen to produce a deliberately jarring aural effect, Sigur Rós' plaintive and ethereal take on "The Rains of Castamere" slots easily into Martin's medieval-esque world. The song, about the destruction of a smaller house that dared to test the might of the Lannisters, was featured in the powerful new episode of the HBO show, which aired last night in the US.