On a corn farm, Spin Kick and Fly Trap are tracking Carmen Sandiego. They follow a signal to a clearing and try to attack. It turns out it is a scarecrow with Carmen's clothes on them. Nearby, Shadowsan smiles, having set the trap, and drives off, satisfied that his goal was accomplished.
In Mexico City, the people are celebrating Day of the Dead. Meanwhile, Carmen is at a museum after realizing that a ton of art has been stolen and this one was yet to be robbed. It includes a particular piece by Frida Kahlo. Carmen notices that one young person is taking notes of all the exits and entrances. After the girl leaves, Carmen decides to wait until she returns to steal a painting.
Meanwhile, in the wrestling arena, Chief notifies Agents Chase Devineaux and Julia Argent of the recent series of museum heists in Mexico City, believing the wrestling match was just a diversion by Carmen Sandiego. However, Julia proposes that Carmen was not here with ill intentions, and she tells Chief that her heart isn't in the game anymore. Julia tenders her resignation and decides to put her second degree to use by becoming an ancient history teacher.
During the Day of the Dead celebrations, the girl thief Sonia reenters the museum, and proceeds to take the painting, Self-Portrait with Monkey. Carmen tries to stop her but she escapes through a window. She brings the portrait to her handler Marta, but it turns out to be just a poster; Carmen had already switched the real one with a fake one.
Marta tells Sonia about a vocational school she recommends for her but Sonia seemingly rejects it, deciding to walk outside. After, Marta contacts Countess Cleo and tells that Sonia would be an ideal candidate for V.I.L.E. Academy.
Sonia returns home, where she lights a candle for her deceased parents. Carmen takes the opportunity to confront Sonia, and tells her not to go down the same path, but gets rebuffed as Sonia shows interest in that.
On the new V.I.L.E. island, the Faculty are having their own Halloween event to themselves. Professor Maelstrom is dressed in a clown costume inspired from IT, with Countess Cleo as Cleopatra, Dr. Bellum as an alien space commander, and Coach Brunt as a cowgirl. They try Scotland's national dish, haggis, but Brunt is revolted and instead answers the door, which happens to be The Cleaners trick or treating.
Carmen confronts Marta, who immediately recognizes her. She tells Carmen that her only flaw is that she cares too much and throws a Pre-Columbian artifact up into the air, forcing Carmen to catch it. However, it was not an artifact but an electro-static shocker device that incapacitates her. Marta takes back the stolen book and puts it in a jar. Then, she drives an unconscious Carmen and ties her on a plane.
Player tells Ivy and Zack he lost contact and they head to the last known location. There, they find the book, and Zack throws up in the same jar. Marta returns and tries to use the same trick that got Carmen, but it has no effect on the siblings. Zack and Ivy head to the airport and see the plane ready to leave. Sonia has boarded it along with Spin Kick and Fly Trap.
The plane takes off but is ordered to land by Marta. In the back of the plane, Sonia secretly tells Carmen that she had a change of heart and was playing along, saying that she didn't want to go to a school for losers. She frees Carmen, and they fight Spin Kick and Fly Trap until the plane lands, escaping with Zack and Ivy.
In a cemetary, Team Red honors the dad of Carmen, and Ivy reassures her that she will find her mother. They discover that the black book is gone, having been stolen by Sonia, who feels obligated to return the items she stole.
After the Faculty is briefed, they look forward to New Orleans, as The Cleaners Boris and Vlad are heading there for an "even greater haunt”.
- Gina Rodriguez as Carmen Sandiego
- Finn Wolfhard as Player
- Abby Trott as Ivy
- Michael Hawley as Zack
- Liam O'Brien as Professor Maelstrom, Vlad & Boris
- Mary Elizabeth McGlynn as Coach Brunt
- Toks Olagundye as Countess Cleo & Tour Guide
- Sharon Muthu as Dr. Bellum
- Rafael Petardi as Chase Devineaux
- Charlet Chung as Julia Argent
- Dawnn Lewis as Chief
- Jeannie Tirado as Sonia
- Sylvia Villagran as Marta
- Sarah-Nicole Robles as Fly Trap
- Dante Basco as Spin Kick
In other languages
- Maelstrom is so into Halloween he addresses his fellow Faculty by their costumes.
- Bellum is shown to be silly enough to try drinking through her costume's helmet.