"Memory Blank" is the twenty-first episode of Danny Phantom. After an argument between the two, Sam makes a wish that she never met Danny, only for Desiree to make it come true, taking her to a world where Danny doesn't have his ghost powers.
Danny and Tucker are amazed by a brand new truck, but Sam, however, is against it, considering it a danger to the environment.
She gets an idea for Danny to use his ghost powers to scare people away from the vehicles, but both Danny and Tucker are against that, telling Sam that she had gotten him into trouble before: For example, she had convinced Danny to go into the faulty Fenton Portal, which gave him his powers in the first place.
Sam is annoyed and wishes someone would get rid of the trucks, not noticing that Desiree had heard her wish. Desiree enchants a giant cow statue which comes to life and destroys some of the trucks, also getting Danny and Tucker soaked with milk.
After Danny fights off the giant cow (and removes the milk from them with his intangibility), Sam suddenly sees a poster with three female horror movie stars: Terminatra, Femalien, and Nightmerica in one film. Since the boys promised to spend the Friday with her, she already got tickets for the movie, but Paulina invites Danny, Sam, and Tucker are invited to her Quinceañera.
Paulina's reason for inviting them, however, stems from the fact that she wants to meet Danny Phantom, and since Phantom always shows up around Danny, she figured inviting him and his friends would cause him to come. Excited either way to be invited, Danny and Tucker beg Sam to go, to which she gives in.
Sam then talks to herself, wishfully saying that she wants something to happen to Paulina to cause a cancellation of the said party before she walks off. Desiree, nearby overhearing, grants her "wish" again, and enchants the movie poster.
Mr. Lancer explains the meteor shower that will happen on Paulina's 15th birthday party while Sam sketches in her notebook, designing a logo for Danny later on. Femalien suddenly attacks and everybody runs screaming while Danny hides and goes ghost.
He attacks the giant beast and phases her through the ground (thus forced to ignore an invite from Paulina).
He eventually beats her, and before she disappears, she says Sam's name. Danny fears that Sam might be somewhat involved in the monster's appearance, so he puts the Specter Deflector around her as she gets a bit angry for the accusation.
Paulina suddenly screams and Danny goes ghost. He warns Sam to stay, but after he leaves, she comes after him anyway, still angry for breaking his promise of going to the movies with her on Friday.
Paulina is on her moped and trying to avoid Terminatra as Danny steps in to stop her. The battle leads to a water fountain where Danny turns back to normal. Sam, still wearing the belt, attacks Terminatra and destroys her, and she too says Sam's name before she disappears.
Danny warns Sam to stay away and the two get into a fight before Sam turns away shouting "Danny, I swear, there are days I wish I had never even met you!" Desiree suddenly appears in front of Danny who discovers the more wishes she grants, the more powerful she becomes. By the time Danny realizes the wish Sam made, it is too late to stop Desiree.
The next day, Sam approaches Danny and Tucker, who have no idea who she is. Sam thinks Danny is just pretending they didn't meet and sarcastically says it's hilarious but Danny tells her he's being serious. Elsewhere, Dash and Kwan stuff some nerds into a locker. One of them, Mikey, wishes someone would show them what this feels like.
Desiree comes and grants the wish by turning him into a wolf-like monster. She flies up to Danny who is frightened and powerless, much to her pleasure.
Mikey stuffs Dash and Kwan into a locker then turns back to normal afterwards. Sam notices Desiree and later finds herself missing from a photo of her, Danny and Tucker inside Danny's locker.
Realizing that Desiree must've made it so she and Danny never met Danny has lost his powers by never having gained them in the first place due to her unknowing wish, Sam tries to convince Danny but fails.
To get his attention, Sam tries to make herself pretty, which apparently works, as he finds her attractive. She shows Danny her pictures of them all together, still not getting to him until he sees pictures of his parents' basement.
Sam then reveals that because she was wearing the Specter Deflector, she was unaffected by the powers Desiree used to grant the wish.
Nightmerica suddenly attacks and Sam, realizing that Danny is powerless, battles her. She makes a ski mask out of Tucker's hat and hits Nightmerica with the Jack O' Nine Tails, then traps her in the Fenton Thermos. Danny is now giving her his full attention.
At Danny's house, Sam shuts down the Portal and quickly arranges the settings as seen in a photograph that she took. She throws Danny his jumpsuit and as when he's finished putting it on, she removes his father's face and applies a mysterious logo to his chest.
Danny cautiously goes into the portal, leans against the "On" button and the portal activates, transforming him into Danny Phantom. Jack hears something from downstairs and is shocked to see Danny, who has turned back to normal, kissing Sam in a "Fake-Out Make-Out."
As a result, he forbids his son from seeing "Paulina" again (the name Sam told Jack to be her own).
That night, Sam tells Danny how to work out his ghost powers and Desiree's plans to use everyone's wishes from the meteor shower to gain more strength.
At the night of the party, Desiree appears and Danny tries to fight her, but he has no experience with his ghost powers. Meanwhile, Sam is attacked by living bushes and Tucker is chased by a monster truck from the beginning.
Sam, realizing Desiree grants every single wish, wishes Danny and her had never fought and get everything back to the way it was (while letting him keep his new logo).
Desiree reluctantly grants the wish and Danny, now with all his ghost-hunting memories, sucks Desiree into the Thermos.
Danny then decides to keep the promise he made to Sam and takes her and Tucker to the movies. While there, Sam and Danny each apologize for the way they acted before and all is forgiven.
- Danny makes several mentions to past episodes when arguing with Sam, including that of making the lunch menu purely vegetarian meals in "Mystery Meat," the gorilla incident in "One of a Kind," the garage sale in "Attack of the Killer Garage Sale," and the infamous "Fake-Out Make-Out" in "Shades of Gray."
- Danny also mentions the cellar full of meat under the school from "Mystery Meat" when he phases through the floor in Mr. Lancer's classroom.
- Allusions: See List of allusions
- Goofs: See List of goofs
- Danny blames Sam for the garage sale incident in "Attack of the Killer Garage Sale" when this was actually his idea. The original concept was supposed to have Sam telling Danny to sell his Dad's junk, but it was changed later on.
- This episode marks the point where Danny gets the white "D" logo on his suit. All subsequent episodes and the theme song animation include the logo in his design starting from the next episode, "Doctor's Disorders". Previous episodes were not retroactively edited to include the logo.
- Box Ghost, Vlad Plasmius, Walker, and Skulker make cameos when Danny regains his memory.
- This episode is Desiree's second and final appearance as a main villain and also her final speaking role. She makes non-speaking cameos throughout the remainder of the series.
- This is the first time Sam and Desiree meet. Despite this, Sam somehow recognizes her.
- This is first episode that Jack Fenton appears without Maddie Fenton.
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