Only Murders in the Building Season 3: Killer, Ending & Cast

Hulu’s Only Murders in the Building Season 3 delivers two killers instead of one—Donna DeMeo poisons Ben Glenroy, and her son Cliff shoves him down the Arconia elevator shaft. The finale’s closing minutes reframe everything when Sazz Pataki is shot dead in Charles’ apartment, with Charles confirmed as the intended victim.

Premiere Date: August 8, 2023 ·
Platform: Hulu ·
Announced: July 11, 2022 ·
Stars: Steve Martin, Martin Short, Selena Gomez ·
Episodes: 10

The season runs 10 episodes, each playing into the broader murder mystery framework the series has perfected since its 2021 debut.

Who’s the killer in Only Murders in the Building season 3?

The Season 3 killer question comes with an asterisk most whodunits don’t: two people share responsibility for Ben Glenroy’s death. ScreenRant confirms that Donna DeMeo poisoned Ben on opening night with rat poison baked into a cookie, intending to incapacitate him. But Ben’s death came later, when Cliff DeMeo pushed him down the Arconia elevator shaft after Ben confronted him about the poisoning.

Killer Identity

• Cliff DeMeo: Theater director and producer who shoved Ben down the elevator shaft. His mother Donna had poisoned Ben earlier.
• Donna DeMeo: Cliff’s mother, who has stage four lung cancer, admitted to poisoning Ben but claimed she never intended to kill him—just knock him out.

The reveal comes in the finale’s closing minutes. Mabel pieces together the connection through Cliff’s handkerchief left at the elevator scene. Radio Times notes that Mabel follows Cliff backstage and links him to the elevator through this crucial piece of evidence. Both Donna and Cliff were arrested for Ben’s murder in the season 3 finale.

Connections to Cliff DeMeo

The motive traces back to professional jealousy stoked by Donna. Ben had written a negative review of Cliff’s production that threatened her son’s career trajectory. Donna panicked after seeing her son’s distress over the bad review and decided to incapacitate Ben before opening night. Esquire reports that Ben’s confrontation of Cliff with the toxicology report showing rat poison—”Holy shit, your mom poisoned me”—led directly to the fatal push.

What happened in season three of Only Murders in the Building?

Season 3 picks up months after the events of season 2, returning focus to the Arconia apartment building and its eccentric residents. Paul Rudd joins the cast as Ben Glenroy, a temperamental actor joining Oliver’s Broadway production. The season centers on Ben’s murder, investigation, and the web of suspects that includes nearly everyone connected to the show.

Key Events

• Ben collapses on stage during opening night after eating Donna’s poisoned cookie
• Loretta Durkin (Meryl Streep) falsely confesses to the murder in episode 9 to protect her son Dickie
• The trio—Charles, Oliver, and Mabel—work to entrap the real killer
• Donna confesses to poisoning Ben but claims she didn’t mean to kill him

Bunny Murder Context

While Season 3 investigates Ben’s murder, echoes of the previous season’s Bunny Follia case linger. The Arconia’s dark history of resident deaths continues, with each season adding new layers to the building’s criminal past.

What was Poppy’s motive for killing Bunny?

The Poppy and Becky Butler storyline carries over from earlier seasons, but Season 3 shifts focus entirely to Ben’s murder. The question about Poppy’s motive connects to the broader pattern of Arconia residents with hidden agendas that the show explores across all three seasons.

Poppy’s Role

• Former Rose Cooper impersonator
• Worked with Becky Butler on various schemes
• Connected to building’s underground criminal network

Becky Butler Ties

Becky Butler’s involvement with Poppy reflects the same kind of desperate, secrecy-driven behavior that characterizes Season 3’s murder plot. Both seasons explore how far people will go to protect loved ones—and how quickly those protective instincts can turn deadly.

Who does Mabel date in Only Murders in the Building season 3?

Mabel’s romantic storyline develops alongside the murder investigation. The “Ah, Love!” episode explores her connection with a new character, adding emotional stakes to her investigative work.

Ah, Love! Episode

According to IMDb, Mabel’s romantic subplot provides moments of levity amid the murder mystery. Her relationship developments occur parallel to the main investigation, with the season balancing romance and suspense effectively.

Relationship Details

Mabel remains focused on solving Ben’s murder throughout the season. While romance provides character depth, her investigative commitment becomes the season’s throughline—Esquire notes Mabel was the only one fully committed to solving Ben’s murder by the finale.

Only Murders In The Building Season 3 Ending & Killer Explained

The season 3 finale delivers a two-part resolution: justice for Ben’s murder and a cliffhanger that reframes the entire season. The trio celebrates solving Ben’s murder before an unexpected shooting changes everything.

Ending Summary

After Donna confesses to poisoning Ben, Mabel realizes the full truth. Cliff—not Donna—delivered the killing blow by pushing Ben down the elevator shaft. Den of Geek reports that Cliff confesses and attempts suicide before Donna intervenes. Both are arrested. The podcast trio celebrates their victory, but the season’s final scene upends everything.

Killer Reveal

• Cliff DeMeo: Pushed Ben down the elevator shaft after Ben confronted him about the poisoning
• Donna DeMeo: Poisoned Ben with rat poison in a cookie, but claims she only wanted to knock him out
• Mabel’s realization: Pieces together the timeline through Cliff’s handkerchief

Donna’s confession includes the memorable line: “I wasn’t trying to kill Ben. I just wanted to knock him on his ass.” Esquire captures this darkly comic moment that defines the season’s tone—tragedy wrapped in absurdity.

Timeline of Only Murders in the Building Season 3

Ten episodes trace Ben’s murder from the poisoned opening night through the killer’s arrest and the season’s shocking finale. For more details on this and other controversies, you can read about the Neil Patrick Harris Amy Winehouse cake controversy.

Confirmed vs. Unconfirmed

The line between verified facts and unconfirmed details shapes how viewers understand Season 3’s plot twists.

What the Cast Has Said

“I wasn’t trying to kill Ben. I just wanted to knock him on his ass.”

— Donna DeMeo (character), Season 3 Finale (Esquire recap)

“Holy shit, your mom poisoned me.”

— Ben Glenroy (character), confronting Cliff (Esquire recap)

Selena Gomez has spoken publicly about her work alongside Steve Martin and Martin Short, calling the experience supportive. The Review Geek notes that Loretta joins the trio’s inner sanctum after being cleared of suspicion, suggesting the cast dynamics extend beyond screen relationships.

Summary

Only Murders in the Building Season 3 delivers its most complex murder yet—two killers, one victim, and a Season 4 setup that turns the finale’s celebration into tragedy. Donna DeMeo’s poisoning and Cliff DeMeo’s fatal push represent the season’s dark core: a mother’s desperate protection of her son’s career spiraling into murder. For viewers, the choice is already clear: Hulu subscribers will need to stay tuned for Season 4 to see how Charles survives the shooting meant for him, and whether the trio can solve their most personal case yet.