“I Know What You Did Last Summer” is the first single from Shawn Mendes‘ album Handwritten Revisited, a reissue of his debut album Handwritten, released in November 2015. The track is Camila Cabello’s first solo venture outside of Fifth Harmony.

The song was written by Shawn, Camila and Ido Zmishlany backstage at a Taylor Swift 1989 Tour concert. The song also credits Bill Withers as a lyricist, with the song sampling his 1971 B-side “Ain’t No Sunshine”.

Camila briefly explained the lyrical content of the song for the “Making-Of #IKWYDLS” video:

It’s basically a conversation between two people in a relationship where it’s dying, but nobody wants to admit that it’s dying.