From the introduction:
Tonisborg Island rises toll at the river's mouth, where the silent waters flow sluggishly into the icy sea as it posses by both the island and one of the North's largest cities built on the nearby shore.
The island itself is the outcast suburb of the city, where a thieves' den of seedy establishments, slave auctions, and ramshackle slums nestle between the smugglers' ports that even the town guard ovoids patrolling - all of which is firmly under the thumb of the Order Droconoe. The island rises higher to the south, where atop a high promontory ore scattered the ruins of on old tower - whether built for defense or as a beacon for ships navigating the river, none now remember. Amidst these ruins con be found the entrance to on ancient catacomb.
The ruins ore on open secret, closely guarded by the Order Droconoe and their allies and used for their own purposes. Few, however, of even these rough characters dare to go beyond the first level into the horrid depths below.
What lies deep inside is unknown, but promises incredible wealth and power for the brave explorer to discover or the fool to die trying.
Beware, for it is said that sleeping in the lowest levels ore the nightmare terrors from the times of dork gods and primeval horrors! If you dare enter this dungeon, tread lightly, and pray to the Greater Gods for mercy.
Publisher's blurb:
What is Tonisborg?
In 1973, Greg Svenson created his own mega-dungeon which later was lost for 35 years. It would come to be known as The Lost Dungeons of Tonisborg.
During filming for Secrets of Blackmoor, copies of the maps and room keys were discovered in the private collection of David R. Megarry, author of Dungeon! board game.
Greg Svenson agreed to have his dungeon published as a historical document of early dungeon play.
User summary:
Includes the original dungeon as well as a complete rules system - The Tonisborg edition of Zero Edition Dungeoneering (ZED).