First debuted during The Chainsmokers' Ultra 2018 set and first announced as a single in an Instagram story on October 12th, 2018, “Siren” is a collaboration with French DJ Aazar. Featuring Andrew Taggart’s vocals over a soaring electronic beat, the song is another hard-hitting electronic anthem in the style of “Save Yourself”. The instrumental takes heavy inspiration from Skrillex’s heavy warping bass sounds of the early 2010’s.