Star becomes acting Queen and plans for Marco and his warriors to delay Meteora from reaching Castle Butterfly long enough for Star to find Moon and destroy the monster princess.
Star interviews Eclipsa about what happened to Moon and Meteora. After being filled in, she has her locked away in her room so as not to interfere. She gets word of people having their souls stolen by Meteora and speaks with her council, though she kicks out the Magic High Commission as she blames them for the predicament, and asks for suggestions. She only gets a lackluster response, and even learns that Mina Loveberry has had her soul stolen as well. Star is driven over the edge when the chefs cannot seem to make up their mind what to make for dinner as Moon is usually the one who gives them the menu. Her father River is of no help as he only seems concerned with food, though he does try to encourage her.
In her bedroom, Star speaks with Marco about the events happening and does not know if she can follow up with her mom's rule. Sir Lavabo enters with her cleaned clothes and she gets the idea to send him to hold off Meteora while she finds Moon. Marco is flummoxed by the idea and pulls her aside and tells her that she has gotten desperate. He then suggests that he go and fend off Meteora. Star does not think it wise, but Marco decides to prove his worth to her after reminding her that he has had 16 years of training with Hekapoo. After an impressive fight, she agrees. Marco reminds her that she does not need to act strong around him and the two hug.
Marco forms his team, "The Marc-nificant Seven", which consists of himself, Tom, Hekapoo, Kelly, Jorby, Talon and Pony Head. He plans to make a "doom-nut", a fire trap for Meteora when she arrives. During this time, Tom apologizes to Marco for his past deeds as he wants to start fresh with him. Donning his Princess Turdina disguise, Marco directs Meteora into the trap, during which Jorby's soul is taken. The trap ends up failing and the team do everything they can to stop her. Ultimately, Pony Head's soul gets taken as the team pray for Star to return with Moon.
Star enters the realm of magic and has her shell phone buzz with the message "You are Star Butterfly. You must find your mom and bring her home," every few minutes. She manages to find Moon, who is naked and has recovered the rest of her soul and removed some of her marks from the dark magic, but she has completely forgotten herself. Star slowly begins to forget things about herself as well, but recovers when she removes her shoe. She opens a portal back home, but when Moon comments on how pretty it looks, Star forgets and the two continue to play in the realm of magic.
- Eden Sher as Star Butterfly
- Adam McArthur as Marco Diaz
- Rider Strong as Tom Lucitor
- Esmé Bianco as Eclipsa Butterfly
- Jessica Walter as Meteora Butterfly
- Grey DeLisle as Moon Butterfly
- Jenny Slate as Pony Head
- Dana Davis as Kelly / Lady Whosits
- Zosia Mamet as Hekapoo
- Dominic Bisignano as Jorby
- Fred Tatasciore as Talon Raventalon
- Damon Jones as Sir Lavabo
- Jeffrey Tambor as Glossaryck
- Jonny Rees as Manfred
- Kevin Michael Richardson as Rhombulus
- Carl Weathers as Omnitraxus Prime
- This is the seventh half hour-long episode in the series, following "St. Olga's Reform School for Wayward Princesses", "Storm the Castle", "Bon Bon the Birthday Clown", "Face the Music", "Starcrushed", and "Monster Bash".
- Along with "Conquer", this was the last episode in the series to premiere on Disney XD.
- Star's struggles as acting queen of Mewni share many parallels with her mother's struggles in "Moon the Undaunted".
- Marco is revealed to have retained his sixteen years of fighting experience while pursuing Hekapoo in "Running with Scissors".
- Hekapoo is suggested to have a crush on Talon Raventalon because of his body.
- Tom recalls the events of "Blood Moon Ball", "Mr. Candle Cares", "Friendenemies", "Naysaya", and "Monster Arm".
- Tom's battle outfit shares some similarities with the armor worn by Zuko and the Fire Nation soldiers in Avatar: The Last Airbender, including the top knot in his hair.
- "Marc-nificent Seven" is a reference to the 1960 film The Magnificent Seven, in which a group of seven gunmen are hired to protect a small Mexican village from bandits.
- Marco's sword "El Choppo" is named after real-life Mexican drug lord Joaquín "El Chapo" Guzmán.
- July 13, 2018 (Southeast Asia)
- August 20, 2018 (Latin America)
- November 23, 2018 (Portugal)
- January 20, 2019 (Japan)