Fitting with the premise of the show, most episodes end off on a note that radically changes the dynamic and context of the story. Due to the nature of the trope, all spoilers are unmarked
Season 1
- "True Crime": It's revealed that Mabel knew the victim Tim Kono, and was in a friend group with him and two others.
- "Who Is Tim Kono?": Mabel finishes recording a confession on her iPad, titling it "In Case I'm Next," with the reveal that Zoe died on the last night Mabel's group were all together.
- "How Well Do You Know Your Neighbors?": Despite their podcast only getting a handful of views, Oliver returns to his apartment to find a note threatening him to end the podcast or else, with the perpetrator having broken into his apartment and poisoned his dog.
- "The Sting": Three big ones.
- First, Charles and Oliver find out from Oliver's son that Mabel knew Tim Kono, and she was part of a friend group where one of them was killed, with Oliver's son warning the pair that she's bad news.
- Second, following up on a lead on her own, Mabel is unknowingly stalked by someone in a multi-colored hoodie - who Charles saw heading up the stairs in the Arconia the night of Tim Kono's murder.
- Third, the story jumps forward several months, with Tina Fey's Cinda Canning starting a new podcast about the events in the series, titled "Only Murderers in the Building," indicating that there is more than one perpetrator, and more murders to come (or that she thinks the three protagonists are murderers).
- "Twist": After Charles and Oliver follow Mabel to her cousin Tavo's tattoo shop, Tavo reveals that Tim feared for his life after trying to take down a black market jewelry dealer named Angel. Mabel then catches Oliver and Charles up on all the jewelry she found in Tim's apartment.
- "To Protect and Serve": After Teddy gives Oliver and Charles a check for $50,000, Charles notices the name on the check is Angel Inc., leading them to believe that he's the Angel Tim was trying to bring down, which put him on their Prime Suspect list. Meanwhile, Detective Williams realizes that someone interfered with her investigation and details weren't followed up on, meaning someone at the top wants the case buried. Not being able to reopen the investigation, she secretly sends Charles, Oliver and Mabel Tim Kono's phone in the hopes they will be able to uncover something that will help in their case.
- "The Boy from 6B": After Mabel and Oliver catch Theo stealing jewelry from the dead, he manages to subdue them and call his dad for help and to let him know they know everything. Mabel manages to text Charles and asks him to use THEO as the password for Tim's phone, which is correct. The last shot shows Mabel and Oliver bound and gagged in the back of Theo's van.
- "Fan Fiction": The toxicology report on Tim Kono proves that the cause of death was poisoning. A photo shows Teddy and Theo outside the building at the time of the murder. Charles discovers that Jan has been seriously injured and may already be dead.
- "Double Time": Oliver and Mabel discover that Tim had a bassoon cleaner in his apartment just as Charles discovers that Jan is not the first chair bassoonist as she claimed to be.
- "Open and Shut": Also doubles as one for the entire season. The In Medias Res flashforward from the first episode comes to pass and the figure lying dead in front of Mabel is revealed to be Bunny, stabbed to death with one of Mabel's knitting needles. Charles, Mabel and Oliver are seemingly caught red-handed and are arrested for her murder.
Season 2
- "Persons of Interest": Someone has stolen Bunny's painting and placed it in Charles' apartment in what appears to be an attempt to frame him for her murder. Charles realizes that the man depicted in the painting is his own father.
- "Framed": Bunny left her pet parrot Mrs. Gambolini to Oliver in her will. Mrs. Gambolini squawks that she "knows who did it".
- "The Tell": Oliver's son Will did a DNA test and found that his biological father is of Greek descent, not Irish. Oliver realizes that this means that Teddy Dimas might have had an affair with his wife Roberta that resulted in Will's birth.
- "Performance Review": The episode ends with Mabel apparently encountering the glitter bomb victim on the subway and apparently stabbing him.
- "Flipping the Pieces": Just as the trio realize that Lucy might be in danger, a blackout wipes out power to most of Manhattan.
- "Hello, Darkness": Detective Kreps stops by the Arconia and Mabel notices glitter behind his ear.
- "Sparring Partners": Poppy reveals to Mabel that she is Becky Butler, the alleged murder victim that Cinda Canning's podcast was about. We then get a flashback of Kreps seemingly meeting Cinda and planting evidence for her.
Season 3
- "The Show Must…": Ben Glenroy's dead body falls through the ceiling of the elevator that the trio is in.
- "Sitzprobe": Loretta confesses to Ben's murder (ostensibly to throw suspicion off her long lost son Dickie), which causes Oliver to have another heart attack.
- "Thirty": The trio burst into Loretta's arraignment to prevent her from pleading guilty to a crime she did not commit. They soon discover that Donna, who they know poisoned Ben, is there too.
- "Opening Night": Sazz goes to Charles's apartment to retrieve a bottle of wine and is murdered there.
