In the most recent episode of the hit Hulu series Only Murders in the Building, Steve Martin performed an original song written by Benj Pasek, Justin Paul, Marc Shaiman, and Scott Wittman. The song, which had been teased throughout the season as a nearly impossible to master patter song, contains spoilers for the new season, so tread carefully!

Watch Martin's rendition of “Which of the Pickwick Triplets Did It” in the video above.

In the third season, the amateur podcasting detectives, played by Martin Short, Martin, and Selena Gomez, return with a new mystery at their feet. On opening night of a new Broadway show produced by Oliver (Short), the leading actor (Paul Rudd) falls down dead on stage.

READ: Season 3 of Only Murders in the Building Called in Some of Broadway's Best to Write Show Tunes

Oliver's fictional musical in the show, Death Rattle Dazzle, needed real Broadway-type music to be featured on screen. The show's co-creator, John Joffman, called in Pasek and Paul (Dear Evan Hansen, The Greatest Showman) to compose the songs, and they signed on under one special condition: that they could bring on additional Broadway songwriters to help them.

The music team quickly turned into a big Broadway roster, with Martin's character's song written by Some Like It Hot's Shaiman and Wittman, and an additional song for Meryl Streep written by A Strange Loop's Pulitzer and Tony-winning writer Michael R. Jackson. Pop star and Waitress composer and creator Sara Bareilles also co-wrote a duet for Streep and Ashley Park.

Only Murders in the Building is available to stream on Hulu.