McMystery at McDuck McManor! is the thirteenth episode of the animated series, DuckTales. It premiered on May 25, 2018 on Disney Channel.
When Scrooge McDuck disappears during his birthday party, Huey, Dewey and Louie find themselves hosting a mystery party where everyone is a suspect.
The nephews are perturbed when Webby, Mrs. Beakley, and their uncle Donald all choose the same moment to leave McDuck Manor, Donald showing particular haste. Mrs. Beakley reluctantly explains that it is Scrooge's birthday, and Huey is immediately intent on throwing a party for his great-uncle. Beakley and Webby warn him against it, revealing that Scrooge hates his birthday (due to the reminder that he is the oldest person he knows), and has disliked parties since before the death of his butler Duckworth. Huey remains adamant, however, and the pair leave for an annual retreat to a secret island to practice their survival skills.
Much to Scrooge's dismay, the nephews end up throwing him a party, with Dewey adopting a masked DJ persona parodying Daft Punk while Louie invites several guests, all members of Duckburg's elite (making it a costume party to throw off the paparazzi). Despite Huey's efforts, Scrooge proves an unwilling participant at the events. Huey then introduces the entertainment, magician Nik Nokturne, but Scrooge is utterly unimpressed by his act. Nokturne then has Scrooge take part in his disappearing act, only for the lights to go down. After a mysterious voice speaks in the blackout, the lights come up to reveal Nokturne's box smashed and Scrooge was gone, having left behind his wallet. Huey then figures out that all the doors are locked, meaning no one could have entered or exited the scene of the crime.
Huey becomes determined to discover who has caused Scrooge's disappearance, and begins his accusations with Nokturne, who is revealed to be Black Arts Beagle. One of the masked guests proves to be Ma Beagle, who becomes annoyed as Black Arts reveals their plans. It is then revealed that they were out to steal the deed to Duckburg, which Scrooge acquired from Grandpappy Beagle after he stole it from the citizens of Duckburg (which he uses to make a profit by leasing the land he owns to other people). Huey then learns that Louie invited Ma Beagle, who denies abducting Scrooge, and discovers that Scrooge's DT-87 security system has been hacked.
This revelation leads to the discovery that one of the other guests is Mark Beaks, whom Louie also invited due to having limited time to prepare. However, like the Beagles, Beaks is uninvolved with Scrooge's disappearance, having been interested in finding footage to humiliate Scrooge for internet publicity, rather than harm him. A photo taken by Beaks at the time the lights went out reveals that the last guest is Flintheart Glomgold. However, his intent was to kill Scrooge-at which he failed miserably as usual-thus leaving the identity of Scrooge's abductor a mystery.
Left at a loss, Huey remains determined to identify the perpetrator, but his accusations of Ma Beagle, Mark Beaks, and Glomgold are followed by their disappearances. It is then revealed that Black Arts possesses actual magical abilities as he summons a demonic spirit. He then reveals that he enacted his own scheme to prove himself to Ma before eliminating her and the others, but the spirit proves to be beyond his control. The creature makes him disappear and then pursues the nephews, but during the chase, Huey realizes the truth behind matters.
It turns out that Scrooge was safe the entire time, and they watch with him as the villains are driven from the mansion. The demonic spirit is revealed to be none other than Duckworth, conjured up by Black Arts' magic act. He took Scrooge to safety, as the manor was filled with his enemies. He then locked the doors, and smashed Black Arts' box. Huey apologizes to Scrooge, but Scrooge is pleased by this latest party, as the villains have been discouraged from setting foot in McDuck Manor again, and Duckworth's return. Webby and Beakley then return to find Duckworth's ghost waiting for them, much to Beakley's displeasure.
This episode premiered early in Norway, Sweden, Denmark, and the Netherlands.
Dewey's "DJ Daft Duck" persona is a parody of the band Daft Punk.
The model number of the security system is DT-87, likely a reference to the original series (DuckTales was released in 1987).
The demonic, skull-faced apparition from the opening credits of the series is revealed to be a shape taken by ghost Duckworth.
The cast performed a live reading of this episode at the Disney Channel Go! Fan Fest at Disneyland Resort, complete with Ben Schwartz holding a keytar programmed with Dewey's lines from the episode.