EP Dan Fogelman spoke with ET about that major cameo and what's to come in season 3.
Spoiler alert! Spoilers ahead for the season 2 finale of Only Murders in the Building, "I Know Who Did It." Read on only if you also know whodunnit!
Only Murders in the Building's season 2 finale ended with a killer reveal and a whole new mystery! The Hulu comedy capped off its second season on Tuesday with the unlikely trio of Charles-Haden Savage (Steve Martin), Oliver Putnam (Martin Short), and Mabel Mora (Selena Gomez) solving their second murder in as many years.
The friends and podcast hosts rounded up their neighbors at the Arconia to play out the dramatic reveal of their suspicions about the murder of surly former resident Bunny Folger (Jayne Houdyshell). They first pointed the finger at rival podcaster Cinda Canning (Tina Fey) and then at mysterious artist Alice Banks (Cara Delevingne), but both accusations were red herrings, meant to draw out a confession from the true killer: Cinda's assistant, Poppy (Adina Verson), aka Becky Butler -- who had been revealed as the subject of Cinda's hit podcast, All Is Not OK in Oklahoma, in the penultimate episode.
But even after Poppy/Becky confessed and was taken away by Detective Williams (Da'Vine Joy Randolph), the mysteries continued. The last moments of the finale flashed forward a year to opening night of Oliver's triumphant directorial return to Broadway. With Mabel in the audience to support her friends, and Charles-Haden taking the stage as one of the stars, Oliver first had some fires to put out with his leading man, Ben Glenroy (Paul Rudd).
Ben insinuated that he and Charles-Haden had been feuding over the course of the production so far, and even went so far as to threaten, "I just might [kill him], I'm warning you."
The pair exchanged tense words as they took the stage together, with Charles-Haden cautioning ominously, "Be smart, stay away from her... I know what you did."
Ultimately, Ben's rage didn't amount to much more than a new mystery, as he dropped dead on stage in the show's opening moments, leaving the central trio in disbelief that murders don't only happen in the building at the Arconia.
"Season 3 is set up," Martin shared with ET of the Murders to come. "I believe in a complete story per year. I don't believe in [a cliffhanger] so every year they never solve the crime -- we actually solve the crime and then we will introduce a teaser for next year."
ET also spoke with Only Murders EP Dan Fogelman at the Hollywood Critics Association TV Awards earlier this month, where he opened up about landing Rudd for the cameo and hinted at his plans for season 3.
"All I will say is that doors open up to you when you have Steve Martin, Martin Short and Selena Gomez in your television show, and if they make a couple of telephone calls for you," he noted with a laugh. "That has been our North star and our lucky star since we started it, and it continues to work for us."
The This Is Us creator also shared that the Only Murders team is currently at work crafting the third season's mysteries, adding, "It's going to be a big season, and I think people are going to love Paul."
As for Martin's recent claims that the Hulu mystery-comedy will be his final acting job, Fogelman says he doesn't believe it. Or, at least, he doesn't want to.
"I think Steve is a worker, and I have big plans to keep Only Murders going for quite a long time, so I don't think that's going to happen anytime immediately," he said. "He's obviously one of the most brilliant minds, comedically and otherwise, that we've had for decades... The day Steve hangs it up will be a sad day for comedy and writing and performing, and so I'm hopeful it happens later rather than sooner."
Only Murders in the Building seasons 1 and 2 are streaming now on Hulu.