The 'Let's Go Surfing' band suffered the loss of their guitarist Adam Kessler earlier this month - two days before they started their first ever US tour - but frontman Jonathan Pierce said immediately afterward the rest of the group, which includes Jacob Graham and Connor Hardwick, stayed up all night then went into the studio the next day.
He told NME magazine: "The next day the three of us got together and started talking over coffee in New York. We went to the studio that day and wrote and recorded what I hope to be the first song on our next album.
"We really feel like it's the best song that we've ever written. It was a pretty emotional day for all of us. I mean, losing a band member and then coming out the other side of it with this incredible song."
Jonathan further explained the track, saying it is "kind of" about Adam's sudden departure.
He added: "It's sort of a goodbye song - but it's not sentimental. It's not sad. It's not sad. It's more of an angry sort of thing. We wrote I guess it's more about feeling betrayed than feeling sad."
Jonathan also said he wasn't sure if the band would "ever want to see Adam again."