Songfacts®:

• Perry Smith (October 27, 1928 - April 14, 1965) was one of two ex-convicts convicted and executed for a 1959 quadruple murder during a home invasion of the Clutter family in Kansas. The crime was made famous by Truman Capote in his 1966 non-fiction novel In Cold Blood. Frontman Dan Smith was taken aback by the book when he read it and "Four Walls" came from it. He told Radio.com:
  
  "I think that's the thing that's so interesting with In Cold Blood, it's so beautifully written, and it's such an engagingly constructed kind of narrative, but then you constantly remember that this actually happened. There's something about watching fiction or reading fiction and knowing that it's fiction where it's maybe not as disturbing as it should be. But then knowing these things [in In Cold Blood] are real, there's something so eerie and creepy about that. And I remember constantly having that realization with that book when I was reading it.
  
  And then the same with that O.J. show, or Making a Murder or Serial, I think also the idea of it being told in a book or a live podcast where you're not seeing anything, so the image you have in your head is entirely your own, I think is really interesting. You can both have read this book and have the same experience and also a really different experience in terms of how you picture it in your head."
• Will Farquarson's bluesy guitar solo at the end was recorded on a tour bus in Germany back in 2014. He told Radio.com: "I listen to the least amount of modern music of everyone in the band. I grew up listening to Hendrix and B.B. King and all these old guys like that. So the minute I was given free range to express myself, I was like, 'Ah, yeah, cheesy blues!' I think it's quite nicely juxtaposed against the track itself, which is very electronic and not bluesy at all."