Originally published in 1981, The Isle of Dread was included in every Expert Rules boxed set as an introductory wilderness adventure. The copy I have is the second version, revised to match up with the Mentzer revision of the Expert Rules. Mostly this involves a number of monsters being replaced due to being left out of the new rules (giant squids were replaced with water termites, a sea dragon with a hydra, and so forth.)
At its core, The Isle of Dread is an adventure inspired by Skull Island from King Kong. The party come into possession of pages from a ship's log describing the discovery of a mysterious island, the natives of which live on a small peninsula separated from the main island by a massive protective wall. The natives claim an ancient city in the center of the island holds great treasure, and the adventure assumes the lure of both exploration and profit will be enough to get the players hooked (a reasonable assumption.)
|I suspect every D&D player above a certain age|
recognizes this map.
On reaching the island the party finds an island of jungles and hills populated primarily by giant animals and dinosaurs (no giant apes, however.) The adventure itself consists of exploring the island, fighting monsters for their treasure, and ultimately reaching the island's central plateau where a temple ruin provides a short dungeon delve. It's less about the individual encounters on the island and more about the overall feel of exploration in uncharted wilderness far from civilization.
The Isle of Dread is also the adventure module that first provides a map of Mystara (though it's not called that yet, the map is simply of 'The Continent') and details each of the major countries shown on the map. One full page at the front of the adventure consists of a paragraph or two for each country, and is where things are established such as Glantri being a magocracy, Darokin's status as a merchant republic, or the Heldann Freeholds' resemblance to ancient Ireland. All of this information would be expanded on in later adventures and in the Gazetteers, but this is where it all started.
|It's not even the Known World yet at this point.|
A number of important creatures are introduced in this module as well, including nearly a dozen dinosaurs and other prehistoric creatures, including giant ground sloths and giant elk. There's a definite 'land that time forgot' feel to the whole thing. Also, a few new sentient races make their debut here, such as the aranea (giant spell-casting spiders), the phanaton (halfling-sized racoon / flying squirrel people), and the kopru (evil amphibious beings with mind control powers). This is also where the rakasta, a race of cat people, first appear; they go on to become an important race in Mystara, with other rakasta tribes showing up elsewhere in the world, as well as on the moon. Not the one you can see, the invisible moon. The moon rakasta ride flying sabertooth tigers and are patterned on feudal Japan. Rakasta are awesome, is what I'm saying.
I'm pretty sure this is the adventure I've run more than any other over the years; I can think of at least four separate campaigns that have visited it. I actually made a point of not using The Isle of Dread at level in one campaign since I knew many of the players had experienced it already. Instead I planned to have the party visit it much later, well after it had been discovered and explored by others. In more than one campaign players have planned to claim the island and make it their domain once their characters were high enough level and sufficiently wealthy to build strongholds.
Next week we'll move on to Module X2: Castle Amber, one of the weirdest adventure modules you'll ever see, and another that turns out be important to the development of Mystara. Also, part of it is set in France.