Dexter's Laboratory Issue #3 is the third issue of IDW Comics' Dexter's Laboratory comic book series. Unlike DC Comics' Dexter's Laboratory comics, the IDW comics consists of only four issues (not counting the unrelated crossovers that followed) and each issue is not a stand-alone story, instead they are part of an overarching storyline involving Dexter's attempts to bring back his sister Dee Dee.
After finally finding the universe where the Dreamwish-O-Tron 5000 had sent Dee Dee to, Dexter is shocked and amazed by the sights of this new world, which looks like a pink and enchanted kingdom inhabited by puppies, kittens, butterflies and unicorns. As he explores this new land, Dexter is soon arrested by the captains of the royal guards, who are none other than Lee Lee and Mee Mee, after being recognized as an outsider in the Land of Dee. They then take Dexter to the royal castle to have an audience with their princess. Upon arriving at the castle, Dexter is greeted by Dee Dee's ex-boyfriend Beau who now serves the princess of the kingdom. Upon arriving in the throne room, Dexter is introduced to Princess Dee Dee, the ruler of the Land of Dee. Dexter quickly tries to remind his sister who he is but to no avail as she nor anyone else remembers him or their past lives. His teleporter remote for returning home is then confiscated and given to the princess. Dexter then sees this as an opportunity to coax Dee Dee into pushing the button, which would instantly return them home and undo the mess, but much to his shock Dee Dee is now a cold and uncaring royal with no interests in buttons or technology, having a subconscious hatred towards it (possibly due to that it was Dexter's tech that erased her out of existence). She then has Dexter thrown in the dungeon to await further punishment.
Once in the dungeon, Dexter soon realizes the futility of his situation, but just then he is given his meal by one of the guards which has the remote control home inside it. The guard outside is then revealed to be Lee Lee, who, despite the change in realities, still has romantic feelings for Dexter but is then called away before Dexter can realize this. As Dexter grabs his remote, a brick from the floor comes loose and out comes a glowing little ball of light which begs him to follow it. The little orb then leads him outside to freedom, and before his doubtful eyes, the orb transforms into a tall Fairy Princess, who reveals herself to be the original ruler of the land. She then explains that Dee Dee suddenly appeared one day with powerful dream-based abilities, which allowed her to take the crown from the princess and take over her enchanted world with ease, as apparently the Dreamwish-O-Tron made Dee Dee's dreams come true as well when she was being banished, sending her to an enchanted world of her liking where she could rule as its new princess. The princess then begs for Dexter's aid in regaining her throne which Dexter agrees to. She then offers him a bag of fairy dust to aid him, but Dexter proves unreasonably stubborn in wanting to use magic, but eventually complies with the princess' request.
Dexter then prepares to re-enter the castle and take his sister home. To do so, he dons on his old girly outfit to pass off as one of the guards. Once inside, he removes the disguise but is quickly caught by Dee Dee and the guards. Princess Dee Dee then makes note that the dungeon was not good enough for her prisoner and decides to give him an even worse punishment...
- This is the second time Dee Dee has visited an enchanted kingdom, the first being Koosland.
- Like in "The Magic Moment", Dexter is portrayed as being very hostile towards magic and with a stern disbelief towards it, despite that in seasons 1 and 2 he had no issues with it and even witnessed it on occasion.
- Despite that the Dreamwish-O-Tron was designed to only send Dee Dee away, many lookalikes of her such as Lee Lee and Mee Mee were also banished, as well Dee Dee's ex-boyfriend Beau. The reason for this is never clearly given.
- It is possible that the device also banished anything and anyone that remotely reminded Dexter of Dee Dee.
- Despite being called a fairy, the princess has no wings.
- The name of the kingdom, "The Land of Dee", may be a reference to the Land of Oz, the main setting in many of the books by L. Frank Baum.