Mr. Rogers: My airplane, where is it?
Eddie: You finally got to the big one, Mr. Rogers. All this is circumstantial evidence. Without the X-7, you've got nothing.
Eddie: You finally got to the big one, Mr. Rogers. All this is circumstantial evidence. Without the X-7, you've got nothing.
— "The Disappearing Airport Caper"
Despite its Short-Runner status, Clue Club has many likable and ingenious perpetrators of seemingly impossible crimes.
All spoilers are unmarked. You Have Been Warned!
- "The Paper Shaper Caper": The Great Mephisto is a Stage Magician who joins a counterfeiting operation seeking to save the theater where he works from being condemned. When their printing press is damaged, he and his boss steal a new one from the newspaperman who got the theater condemned in the first place. He uses intimidating disguises and magic tricks to try and scare the kids off the case, but he and his partner are also the only villains in the show to see the advantage of spying on the kids and learning about their progress with a human disguise rather than a ghost one. While his boss is captured at the end of the episode, Mephisto remains at large.
- "The Real Gone Gondola": Tom Coldwell schemes to kidnap his paraplegic aunt Clara and fake her death so he can inherit her ski resort and sell it for a million dollars. He is well-liked by everyone and seems to have no desire to genuinely harm his aunt. After kidnapping Clara, Tom dresses a balloon in Clara's clothes and wheels it onto a gondola. He pops the balloon and takes it with him while making an excuse to leave the gondola, then pulling a lever to send it heading up the slope, as if Clara started it herself. Tom also sends a letter from a supposed Mad Scientist extortionist threatening to disintegrate Clara and their other guests to cover his crime. Tom then works to scare everyone away from the shack Clara is imprisoned in until he can sell the resort. He uses gimmicks like a remote-controlled snowmobile and a living snowman disguise. When Clara is rescued seconds before Tom can sell the resort, he does a good job of acting happy at her return, before giving up and going away quietly once the case against him is laid out.
- "Who's To Blame for the Empty Frame": Harvey Tobias and Martin Carlottie are a clock repairman and a 3-foot tall pantomime artist who conspire to rob one of Tobias's clients, a rich antique collector. Carlottie poses as a clock figure to be able together past Harrison's security system and steal the best items in his collection late at night. He hides a painting in the back of a mirror that Tobias pretends to damage by accident so he can have an excuse to take it off the premises, supposedly for repairs. The two men are exposed and confronted after robbing Harrison a second time, at which point an unfazed Carlottie bows to the investigators. They don't panic and deny their guilt, with Carlottie pointing out that the crimes that can be proven against them lack any significant punishment. When the painting is found in Tobias's shop, though, Carlottie tells Tobias that denying their guilt is futile, and Tobias agrees, musing how it is only the unexpected presence of the Clue Club that kept the plan from succeeding.
- "The Green Thumb Caper": Melinda Carter and Joseph Wilkins are a pair of jewel thieves who pose as a gardener who provides floral arrangements and a butler. At several charity fundraisers they are hired to work at they turn off the lights, then rob the guests while using an ultraviolet flashlight, the beams of which can only be seen with ultraviolet goggles. The duo cover the stolen valuables in gravy and feed them to Carter's beloved Venus flytraps to smuggle them out amidst the police searches. When the Clue Club uncovers evidence of their crimes, a disguised Wilkins tries to steal it back before Dotty can analyze it. After discarding his disguise, he acts like a source of helpful information while subtly making Larry suspicious of the Impoverished Patrician hosting the charity parties. When the two are exposed, Carter does an impressive job of acting innocent and accusing Wilkins of using her and her poor innocent Venus flytraps before being taken in.
- "The Disappearing Airport Caper": Eddie is a mechanic who plots to steal a valuable experimental jet. Eddie jams the pilot's radio and sonar, then sets up fake landing lights to make the jet land at nearby farm on a foggy night. Eddie disguises a Quonset hut as the airport's hanger. Obscuring his face, he sends the tired pilot to a shack to get some sleep. He wears his own name tag and distinctive baseball cap after reporting it stolen to make it seem like someone is trying to frame him. Eddie then removes the lights and Quonset hut and hides the jet beneath a haystack. The pilot wakes up surround by cows and hay, with no trace of the plane or the airport. Eddie acts helpful and cordial throughout the episode, inviting the heroes to watch him demonstrate a remote-controlled plane. Even when the plane is recovered, it is unclear if the heroes have enough evidence to have Eddie arrested for the crime.
- "The Walking House Caper": Mr. Benchley is a rural general store owner who—according to Larry—schemes to steal a valuable steel formula to sell it for the money to buy back land that once belonged to his family before an amusement park company can purchase it. The formula is being kept in a safe made of the new steel process and will take days, weeks, or even months to break into. Benchley uses sleeping gas to knock out the Clue Club as they guard the formula, then takes them to a nearby house that looks exactly the same inside and outside, while making an empty impression in the floor where the safe is in the original house. When the kids investigate, Benchley acts like an interested, innocent man and a source of useful local lore. Benchley gracefully apologizes and gives Woofer and Wimper dog biscuits when his guard lobster bites their tails. It is also implied that he has an accomplice and that they take turns scaring people away in a monster costume so that Benchley will have an alibi.
- "The Dissolving Statue Caper": Dave Crane steals a fifteen-ton statue meant to benefit a failing theme park. Crane makes a copy of the statue out of cotton candy and uses his helicopter to fly it to a fair as he has been contracted to while hiding the original nearby. Crane then trains his pet monkey Sheena to spray the cotton candy statue with a hose, melting it after the fair employees cover it in a tarp. This causes the statue to vanish from under the nose of hundreds of people while Crane is miles away. Crane alternately chases DD and Pepper in a clown outfit and speaks to Larry without the costume to try and establish an alibi. When he's exposed, Crane gracefully confesses and asks an acquaintance to give Sheena a good home while he's in prison.
- "One of Our Elephants Is Missing": Chris Carloff is an exotic animal supplier for zoos who decides to rob one of his clients to supply the others while also making the zoo he robs come to him for replacement animals. Carloff and an accomplice abduct several zoo animals in the middle of the night. Carloff then dresses up as a gorilla that they stole and remains behind. He uses his gorilla disguise to spy on the investigation, plan a second string of kidnappings, and divert the detectives by acting like a wild and angry animal. He puts a stuffed gorilla in his cage while he sneaks out and meet with the zoo director, establishing an alibi for himself for when he plans to reveal the gorilla was a human imposter. Upon being confronted with the evidence against him, Carloff responds bitterly, but also recognizes that it's futile to deny the truth, and confirms Larry's hypothesis is right.
- "The Amazing Heist": Madame Hortense and Oslanski, an elderly convention center owner and her maintience man, are the deposed princess and prime minister of the European nation of Dileria. When a Dilerian crown which Hortense sees as her birthright comes through town, Hortense arranges for it to be displayed at her center and the two engineer a blackout and steal it, using Oslanski's skills with electronics and trap doors. They deliberately violate local sanitation laws by leaving a pile of trash in the hall so that Oslanski can smuggle the crown out of the building under the guise of complying with Sheriff Bagley's inevitable order to get rid of the garbage. Hortense works hard to make Oslanski seem Beneath Notice during the investigation, but fails, leading to the pair's exposure. They defiantly reveal their real identities and insist that Hortense is the crown's rightful owner, something that Bagley seems to consider and advises them to argue in court as he arrests them.
- "The Prehistoric Monster Caper": Alan Wolf is the former co-owner of a movie production company, reduced to working as a prop man after his partner, Simmons, swindled him out of his share. He kidnaps Simmons and disguises himself as Simmons to enter a crane hoist before using mountain-climbing gear to sneak down while a fog machine is obscuring everyone's view. Wolf tries to scare the Clue Club away from where he is keeping Simmons, brings up other people's motives, and freely admits that he has a motive to kidnap Simmons while nearly fooling them into thinking he lacks the skills to be guilty. When Larry figures out the truth, Wolf compliments his intelligence while refusing to admit anything and arguing that they need a witness to prove his guilt. Once Simmons is rescued and identifies him, Wolf quietly accepts his defeat.
