Five children at an amusement park enter a portal into another realm while riding on a rollercoaster, and find themselves in a strange world harboring dangerous creatures and a multitude of strangers who have alterior motives. The kids - namely Hank [Willie Aames], Eric [Don Most], Diana [Tonia Gayle Smith], Presto [Adam Rich], Sheila [Katie Leigh] and Bobby [Teddy Field III] are granted traditional character classes of Dungeons and Dragons (Ranger, Cavalier, Acrobat, Magician, Thief and Barbarian, respectively), by Dungeonmaster [Sidney Miller]: a tiny grinning man who appears periodically to leave a tidbit of information before blinking out of sight, without a trace. Accompanying them is their 'pet' of a baby unicorn, simply known as "Uni" [Frank Welker], who cannot talk but merely "baa"s like a sheep.

The premise: getting back home...which is not an easy task, as the kids travel across vast and strange lands and encounter various monsters taken directly from the role playing game itself. Their main concerns are the wise yet vicious 5-headed monstrosity Tiamat [voiced by Frank Welker], whose multicolored heads each spit a different element: Fire, Ice, Lightning, Acid and Gas. Venger, their main enemy, is a powerful and evil mage, and uses several henchmen to seek out the kids, such as Shadowdemon - a spectre who scouts the kids' movement throughout the realm.

The series brought about a fascinating blend of styles, from its overall serious, dramatic premise, to comedic elements (Presto's bottomless pit of a hat, in which he pulled ridiculous items from - or Eric's short temper and constant complaining), as well as the writer's attempt to create a sense of abandonment and loathing in the characters' situation of being far from home.

• "Dungeons and Dragons," the role playing game and the cartoon, faced heavy criticism in the 80s, due to criticism for promoting or glamorizing witchcraft. The cartoon faced heavy criticism for violence by Broadcast Standards and Practices, and episodes such as "The Dragon's Graveyard" were nearly banished from TV due to the strict perception of violent themes in children's programming.
• Show writer Michael Reaves had finished a final 28th episode named "Requiem," which never materialized into a completed episode to be shown on TV. [SPOILER:] Dungeonmaster presumably betrays the children. Given a proposal by Venger, the kids are told to find a key to a tomb, which must be cast into the abyss, for the gift of their safe return home. They kids later decide, during a huge battle, to open a lock near the tomb with the key rather than obey Venger. This casts a spell on Venger, returning him to his former good self, as he proclaims the Dungeonmaster as his father. Dungeonmaster presents a portal back to the amusement park, with a choice to either stay in the realm for more adventures, or to return home. The result of their decision is never revealed.
• A rumor persisted about the final episode, in which it revealed that all of the children were killed during the opening sequence of the first episode, and you had been seeing their torment in Pergutory or Hell throughout the entire series, with the Dungeonmaster being the devil in disguise. This rumor was dismissed by writer Michael Reaves.