When Lucy was younger they'd cook together at the Arconia and sing "Angel in Flip-Flops," which was a huge hit in Germany.
So what inspired the hilarious cheesy tune? Is "Angel in Flip-Flops" actually a clue in the case of who murdered Bunny (Jayne Houdyshell)?
Here's what we know.
Was "Angel in Flip-Flops" a nod to Steve Martin's musical career?
In addition to being an iconic comedic actor, Steve Martin is also quite the accomplished musician (save some talent for the rest of us, Steve!). He wrote the book and lyrics for two Broadway musicals: Bright Star and Meteor Shower.
Steve's first solo music album The Crow: New Songs for the 5-String Banjo was even awarded a Grammy for Best Bluegrass Album!
Although Steve's musical ability is quite legit in real life, Charles' song "Angel in Flip-Flops" only appeared to top the lower end of the charts in Germany. However, Charles is thrilled when Mabel (Selena Gomez) realizes that part of "Angel in Flip-Flops" had been sampled in other songs by popular artists.
As a result, Charles banks about $200,000 annually in royalties from "Angel in Flip-Flops." It certainly helps pay the rent at the Arconia!
At the moment, "Angel in Flip-Flops" doesn't appear to be a clue in our trio's ongoing investigation into Bunny's murderer. However, Charles's hit single serves a bridge from the past to the present. Lucy happily joins in when Charles starts singing the melody in the present day, just like the pair did in the past.
Maybe Oliver can craft a musical around "Angel in Flip-Flops," after he, Charles, and Mabel clear their good names!
However, let's not write out "Angel in Flip-Flops" as a clue just yet. As Decider pointed out, the Only Murders in the Building Twitter actually released a series of puzzle-piece clues on its page that eventually revealed the album cover of "Angel in Flip-Flops."
Also, during the show's opening credits, there's a pair of flip-flops hanging from a tree in front of the Arconia. Coincidence? Nothing in Only Murders in the Building ever is!
We know that Lucy heard Bunny's killer when she was hiding out in the Arconia's secret passageway. And for some reason, the killer keeps planting evidence in Charles' apartment. Episode 4 ended with Charles seeking out his murderous ex-girlfriend Jan (Amy Ryan) after she called him a million times.
Could there be another piece of evidence hidden in Charles' "Angel in Flip-Flops" record?
Although the mystery of Bunny's murder still remains unsolved, we think everyone can agree that "Angel in Flip-Flops" is a certified bop!
You can catch new episodes of Only Murders in the Building Season 2 Tuesdays on Hulu.