Lena's loyalties are tested when Magica forces her to lead Webby on a raid to a facility full of Scrooge's most dangerous artifacts to find his #1 Dime.
During Webby's sleepover at McDuck Manor, Lena tries to steal the Number One Dime off Scrooge's neck while asleep. However, Webby draws her attention to the room to find Lena. Scrooge begins waking up from a nightmare that prompts Lena to drag Webby out of Scrooge's room. Webby interrogates Lena before Lena can come up with an excuse; preying on Webby's obsession with Scrooge, Lena suggests they check out Scrooge's Number One Dime, though Webby instead chooses to read to Lena The Life and Times of Scrooge McDuck biography.
Meanwhile, Louie takes advantage of Dewey's ambition to do his laundry. Huey is mad with Louie for doing this before he then gets cautious when Louie finds more of his hoodies destroyed. Magica De Spell overhears Scrooge confiding with Mrs. Beakley over the possibility that something has infiltrated the manor and targeting his dime, so Scrooge has it placed in his "other bin" until he can hunt down the intruder. Shocked, Magica instructs Lena to actively use Webby this time. When Lena asks Webby what the "other bin" is, Webby reluctantly answers that the site is where Scrooge keeps his most dangerous artifacts. Lena convinces Webby to come along to see Scrooge's belongings.
Having overheard Scrooge's talk, Huey thinks Scrooge is catching on to him hoarding a sasquatch named Tenderfeet, which his brothers have found once he returns to the room. Huey took Tenderfeet in when he helped remove a thorn from the sasquatch. He gets onto Louie's nerves and urges them to turn Tenderfoot in but his brothers coerce Louie to keep the secret by threatening to reveal Louie's own schemes.
Lena and Webby go to the garage and find a secret passageway to the Other Bin, which contains several guarded vaults. Lena opens one of the vaults containing a violent unicorn that charges at Webby. Noticing Webby in danger, Lena throws her the diamond dagger she used earlier to help her to recapture the unicorn. Webby discovers that the serial numbers on each vault correspond to dates the artifacts were captured and traces the dime to its vault.
Louie soon realizes that Tenderfeet is a con named Gavin who was scamming the boys to crash at the manor. Gavin, however, threatens Louie to keep quiet about it for his safety from the sasquatch. Later, Louie shaves off hair from Gavin to convince his brothers that the sasquatch needs to return to the forest. While dragging Gavin back, Scrooge confronts the sasquatch before being convinced by the boys to spare him.
At the bin, Lena locks herself in the vault from Webby and she acquires the dime, allowing Magica freedom. Just as Webby enters the vault using the dagger, Magica reveals Lena's deception. A crushed Webby attempts to alert Scrooge nonetheless, but Magica turns her into a doll before she can. Magica then begins to torment and assault Lena through doll Webby until Lena uses magic to destroy the doll to her horror. However, it turns out to all be a dream incurred by the mystic dreamcatcher that was in the vault. Webby amends her error and is about to lead Lena to the real vault but Lena calls off the search.
Scrooge picks up the dime where he runs into the girls. Lena apologizes for intruding, so Scrooge encourages her to be forward the next time. Before exiting the bin, Lena decides to finally come clean with Scrooge about Magica, but she finds herself unable to admit due to Magica's powers growing stronger from the nearing eclipse. Magica's essence then possesses Lena and she assumes full control of Lena's body.
- David Tennant as Scrooge McDuck
- Danny Pudi as Huey Duck
- Ben Schwartz as Dewey Duck
- Bobby Moynihan as Louie Duck, Bro #3
- Kate Micucci as Webby Vanderquack
- Kimiko Glenn as Lena
- Toks Olagundoye as Bentina Beakley
- Sam Riegel as Tenderfeet/Gavin
- Catherine Tate as Magica De Spell
- Keith Ferguson as Bro #2
- Webby states Scrooge was born in 1867, which makes sense since "The Golden Lagoon of White Agony Plains!" refers to the 1890s Klondike Gold Rush that Scrooge was around for. This is consistent with Don Rosa's timeline for the character utilized in The Life and Times of Scrooge McDuck.
- A Darkwing Duck poster can be seen in the triplets' bedroom.
- The poses of Donald and his nephews together in the photo that Tenderfeet holds references a promotional image from Quack Pack.
- Webby's doll form is based on her 1987 look and her doll.
- The room the Dime is kept in is Scrooge's Worry Room from the Carl Barks comics.