At the Rijksmuseum in Amsterdam, a shadowy figure passes through the night undetected. Her goal is a simple painting of a woman reading a letter, which she escapes with without issue. However footage of the mysterious thief is captured on camera and under review by newly-minted A.C.M.E. agents Chase Devineaux and Julia Argent, along with A.C.M.E.'s chief via holographic transmission. Upon examining the thief's face, Chase exclaims that she is not Carmen Sandiego, which the Chief confirms to be "The Duchess"; a phantom art thief that has never left behind any evidence of her existence until just that night. The stolen painting is "Woman [in Blue] Reading a Letter", one of the only thirty-four paintings known to exist by the artist Johannes Vermeer. Chase is unimpressed by Julia's knowledge of art history but the Chief praises her efforts, which makes Chase feel insignificant. The Chief assigns Chase and Julia to track down the painting and whether or not The Duchess is affiliated with V.I.L.E.
Elsewhere, at a hotel, Carmen is looking upon the painting that A.C.M.E. is looking to retrieve, revealing that Carmen herself is The Duchess. Carmen briefs her team on their current operation: V.I.L.E. operatives have been stealing the works of Vermeer the world over and replacing the paintings with near-immaculate duplicates in order to give the impression that the paintings were not stolen at all. Carmen pinpoints the source of the thefts as V.I.L.E. faculty council member Countess Cleo, the organization's resident art expert. By this point, V.I.L.E. has acquired all but the painting Carmen stole, meaning they now had a near-complete collection. Carmen's intent is to use their theft of the last work of Vermeer to lure Countess Cleo into a sale, thus allowing them to trace the painting to the other thirty-three and steal all of them back.
A knock at the door disrupts the conversation and Zack, thinking it's room service, rushes to answer. Carmen tries to stop him but fails, forcing the entire team to duck out of sight. The man at the door realizes he arrived early due to not adjusting his watch for the time zone he was in, which set him an hour ahead of his appointed meeting. He's about to leave when he eyes the painting he came to buy. Zack, unsure of what his role should be, attempts to play himself off as "The Duke" for the sake of the con. The man in the trenchcoat introduces himself as "Dash Haber", Countess Cleo's courier and art validation specialist. Satisfied the painting is legitimate, he agrees to pay and sets off.
Needing to be led to the other missing paintings, Carmen indicates Zack to insist that he be present for whatever Countess Cleo has planned for the art. After Zack vaguely threatens Dash, Dash contacts Countess Cleo to sort things out. Not wanting to risk things not going as planned, Countess Cleo agrees to deal directly with "The Duke" if it means getting the last Vermeer, and extends an invitation to Zack to attend the dinner party and art auction at her mountain chateau the following day. Although Countess Cleo's decision to auction off paintings she went to the trouble of acquiring seems strange, Carmen rationalizes that their value makes them more worthwhile than the trouble it took to steal. Unfortunately, because of the circumstance of Zack playing the role Carmen was originally going to fill, the team now has to prep Zack to be a convincing duke in time for the event in 24 hours.
Carmen sets out to give Zack a crash course in all things that Countess Cleo might look for which would blow his cover. Shaving down Zack's natural Bostonian accent with proper diction, dressing for the part, proper dinner etiquette, and knowledge of the art world are all crammed into Zack over the course of a single night. Despite being heavily burnt out by the exercise, Zack comes through and is able to pull off the look of a convincing duke when the appointed hour arrives. Zack is met outside the hotel by V.I.L.E.'s "Cleaners" and a bag is put over his head to conceal the route to the chateau. However with Carmen and Ivy on his tail, the effort is in vain. The limousine travels into the mountains of the Netherlands but as they venture to the site, Carmen notices they're being followed by a sleek sports car.
Inside the car following Carmen is Agent Devineaux, who is quite enjoying the upgrade in hardware he has received from A.C.M.E. A call from Julia comes through, informing Chase that the payment method used to pay for the hotel was the same as the one used to rent the van that he is following, suggesting that the van is being driven by "The Duchess." Julia once again attempts to read deeper into the M.O. of the art theft but Chase continues to be obstinate and ignores her, more interested in pursuing the vehicle in the hopes he is dealing with Carmen Sandiego. Carmen opts to shake the tail by leading Chase over a nearby drawbridge, which she instructs Player to hack and open before they cross it. Carmen tells Ivy to try and jump the bridge but Ivy is unwilling to take such a risk and stops short. However Chase does not and sails over the open bridge, barely landing his car on the opposite end. Chase looks back at the van and catches a glimpse of Carmen but before he is able to do anything, his car loses its balance and falls into the river below.
Julia calls in again but notices that Chase's car is submerged. Chase tells her that he now has confirmation that Carmen is involved in the heists and is also affiliated with "The Duchess", whom he claims was present in the van with Carmen. However Julia points out that The Duchess's accessories are still in the hotel room, debunking his theory. Chase sidesteps his error and asks Julia how to eject himself from the car. Carmen and Ivy look into the river, trying to decide between helping or continuing tailing Zack when the decision is made for them as Chase rockets out of the river, having ejected himself from the submerged car, allowing Carmen to resume her own mission.
At the chateau, the Countess introduces herself to "The Duke" and has the money wired in exchange for the painting. Meanwhile, Carmen and Ivy have managed to distract the guard dogs patrolling the perimeter of the estate. Countess Cleo takes Zack's arm and leads him into the dining room of the chateau while Dash is ordered to put the last Vermeer with the rest in Cleo's art vault. Using the combination of a hidden camera inside the painting's transport case and a miniature microphone shaped like a button on Zack's shirt, Player is able to read the passcode for the vault as well as hear what's going on during dinner.
With the last Vermeer secured in the vault, Carmen and Ivy make their move. Using the passcode relayed to them by Player, Carmen and Ivy effortlessly enter Countess Cleo's vault. With Player aligning their timetable to the ongoing dinner, their window of opportunity closes when dessert is served. Each of the paintings is held on a pressure trigger that only gives the thieves a half-second of tolerance before going off, allowing them to swap each painting with an empty frame and not set off the alarm. Zack, although not pulling off the most convincing masquerade, is still able to stay within the Countess's good graces at dinner.
With dessert closing in and several more paintings to swap, Carmen and Ivy are running out of time to complete their objective. However, thankfully an unexpected dish is being served at the table: Beluga caviar. While this buys the duo more time, Zack's aversion to eating anything aquatic comes back to haunt him. Zack comes dangerously close to having to ingest the unwanted food but just as he's about to take his first bite, Chase barges into the room and announces that he is there to apprehend an art thief. Zack takes advantage of the distraction to discard the caviar and Player informs Carmen that Chase's interruption can work in their favor.
Chase circles the tables and explains his reason for being at the chateau. He's about to be taken out by the Cleaners when he informs the attendees that he is interested in the capture of Carmen Sandiego, which causes Zack to spit his water all over Dash. Cleo dismisses the idea that Carmen would be at the chateau but floods the art vault with gas in order to flush out anyone who may be in there. Carmen and Ivy are in the process of swapping out the last painting and manage to equip their gas masks before they're overcome, making their hasty escape from the vault.
Zack quickly points out a red-coated figure making an escape on a snowmobile outside the estate. Chase runs outside and takes a snowmobile for himself to pursue. The figure in red sails over the fence and Chase follows. Meanwhile Countess Cleo visits the art vault to discover all the paintings have been removed, with one frame stamped with the silhouette of Carmen. Cleo orders the chateau scrubbed by the Cleaners.
The red-coated figure is still on the run from Chase, who doggedly stays in pursuit. He successfully overtakes his quarry with a large jump and slides to a halt right in front of the person in red. However when he confronts his target, it's revealed Ivy was wearing Carmen's coat and hat to act as a decoy. Carmen and Zack make a clean getaway with the paintings in their van.
The following day, the chateau now lays in smoldering ruin. A drone flies by and snaps pictures, feeding the images back to A.C.M.E. Chase sheepishly laments that he only found out after the fact that the party he crashed was actually rife with V.I.L.E. operatives. Julia had been watching news feeds about the return of the stolen Vermeer paintings and surmises that Carmen Sandiego's motive for theft is a noble one and may have been soliciting the help of "The Duchess" to accomplish her goal.
Meanwhile, in Sydney, Australia a familiar young man steps off a bus with a bag over his shoulder.
Tropes seen in the episode include:
- Accidental Hero: Chase, albeit unknowingly, saves Zack from nearly blowing his cover as the Duke.
- Brick Joke: Zack makes a comment on how he thought that "Dogs Playing Poker" was considered fine art. Later on, after he completely charmed the Contessa, he notes that Dash Haber considered "Dogs playing Poker" was fine art.
- He Cleans Up Nicely: Zack looks quite spiffy in a suit.
- Nice Job Breaking It, Hero: Carmen already had a plan that she would infiltrate the dinner as "The Duchess". Unfortunately, Zack ruins it by opening the door to see Dash Haber about to greet her (thinking it was his room service) and now they have to change the plan so that it's Zack as "The Duke" to go see him.
- Shout-Out: Carmen has Zack go through narration lessions ala My Fair Lady.
- Spanner in the Works: Zack is about to blow his cover because the final dish on the menu is caviar (and he hates fish). Just as he's about to puke, Chase busts in and Zack can easily toss the caviar away before anyone notices.
