This psychodrama is a duet between Future Islands lead singer Samuel Herring and Debbie Harry of Blondie. It was producer John Congleton's connections that helped the band nail the Blondie front woman for the track. "I didn't actually think 'Shadows' would make the record because we couldn't figure out who should sing on it," said Herring to Q magazine. "It had to be a legend like Debbie Harry or Kate Bush and Kate Bush was an insane prospect."
Congleton, who produced Blondie's 2017 Pollinator album, suggested emailing the track to Harry, who loved it and recorded her part long distance. "John wanted me to tell her what her role was in the song, said Herring. "I said, 'You're like the spirit of the world but also the voice within myself, trying to save me.' I hope this doesn't sound too much. And she said 'No, I'll figure it out.'"