Seventh grader Cornelius Fillmore (voiced by Orlando Brown), a juvenile delinquent with a record, was caught raiding the school's new chalk shipment.

The show is based around him and his partner Ingrid Third (voiced by Tara Strong) at X Middle School, which is located in the suburbs of Minneapolis and Saint Paul in Minnesota.

The series usually presents kid-friendly versions of common crimes, such as stolen scooters, smuggling tartar sauce, holding illegal frog races, and counterfeiting collector cards.

It appears on their album Super Secret, as the intro to the song "Das Über Tüber, or the Mystery of Mr. P." The announcer of the series was voice actor Don LaFontaine, best known for his catchphrase "In a world..." X Middle School's bathroom renovation project teeters on the brink of disaster as the new tagger "STAINLESS" strikes at will.

Out of leads, Fillmore and Ingrid turn to Randall "the Vandal" Julian, another tagger called "FLAVA SAVA", currently in solitary detention.

Guest starring Mae Whitman, Kurtwood Smith, and Josh Peck Randall Julian is a parody of Dr. Hannibal Lecter from The Silence of the Lambs, which the episode shares many similarities with.

Guest starring Kyle Gass and Frankie Muniz The Library's books have disappeared, and Tony Clementina, X Middle School's local heavy, is all too eager to take credit for it.

Guest starring Holly Robinson Peete and Gary Dourdan During an undercover sting operation, boxes of band candy were accidentally discovered in the lake.

The candy is traced back to the Red Robins – seemingly a school club in the same manner as Girl Scouts who make record sales of their award-winning taffy.

In reality, the Robins strong arm their competition (stealing candy and cookie dough, cheating in selling taffy, messing up signs of competitors), and the Safety Patrol have been trying to catch them in the act for a long time.

Fillmore and Ingrid first suspect the RC Car Club to be behind it, but Oscar, the best model railroad engineer at X, seems to be coping extremely well to the tragedy.

Guest starring John Rhys-Davies Mrs. Cornwall's Pre-Algebra final exam looks like it is going to be a tough one, but four of her students have decided to take more extreme measures beyond studying.

Guest starring Holland Taylor Mrs. Lawson's field trip to the Modern Contemporary Natural History, Art, Science and Miniature Museum takes a horrifying turn as someone draws a mustache on the priceless painting "The Lobster Man at Port".

Guest starring Mae Whitman, Richard Riehle, Kristin Chenoweth, and Steven Weber Scooter thefts are up, and the Safety Patrol faces a challenge from student activist Derek Minna, who establishes B.A.G.A.S.T.

Guest starring Daveigh Chase The heat is on from Student Council Representative Peabody to find a stolen case of computer disks holding information on term papers off the street, but the perps always seem one step ahead of the Safety Patrol.

Guest starring Jason Fuchs Vallejo's nearing his second term test for Junior Commissioner, and in the meantime, a crime crops up involving 'The Shredder'- an anonymous criminal who shreds people's pet projects.

He deduces that the Shredder is hitting students from the Drama Club in alphabetical order – and his own sister, Francine, is next on the list, but these shredding incidents are not all they appear to be.

Guest starring Mae Whitman and Kyle Gass Reformed thug Linus Santiago impresses the crowd at the X Middle School Talent Show with his magic act, but his disappearing trick with Dewey Hubble's robotic dog Barcode goes horribly wrong – it will not reappear.

Guest starring Thomas Dekker and R. Lee Ermey X Middle School has become obsessed with Canada – and the ambassador's son is staying over, along with his assistant Penny Madrid, who happens to be an old partner in crime with Fillmore.

Guest starring Francesca Marie Smith Something is down at the X Middle School Open – professional golfers are failing at games, and foul play is suspected.

When a shipment of stolen X Middle School foam spirit lobster claws is tracked back to also-ran Oscar Mabini, it looks like Peter has closed his first case, but all is not what it seems, and family honor has everything to do with it.

Naturally, the main suspects are two members of a rival novel's fanclub – TQ, a mysterious and riddle-talking guy with an affinity for multicultural cuisine, and Trace, a girl who never seems to be happy with the color of her hair, but evidence points to neither.

Guest starring Noel Fisher, A. J. Trauth Guildenstern, the Science Department's tarantula mascot, has been poisoned, and the prime suspect, Eric Orben, has escaped into the city.

Reruns continued until September 2 of the same year, when the series (alongside The Legend of Tarzan and Buzz Lightyear of Star Command) was pre-empted in favor of a 90-minute showing of Recess.