My Songs Know What You Did in the Dark (Light 'Em Up) is a song composed by American pop punk group Fall out Boy released on February 4, 2013, in the United States. The single marks the band's comeback four years of being on an indefinite hiatus in 2009. The band announced that "Light 'Em Up" is the lead single from the fifth studio album "Save Rock and Roll", which was released on April 12, 2013. 