Treasure Hunt (N4) in Mystara
by Marc Saindonan interesting novice adventure, adaptable to Mystara. maybe start the players at level 1 instead of 0 (they still haven't chosen their Archetype/Subclass at level 3, so there's still the "self-discovery aspect"). a few quick ideas on adapting it to Mystara:
The Korinn Archipelago is replaced by Minrothad.
The characters get invited on a Ierendi pleasure cruise, end up being drugged and captured, and are sent to Thyatis to be sold as slaves.
Hafkris is a just a really ugly human, not an half-orc. Add in some lore about him being a low-ranking member of the Iron Ring, to establish a future villainous faction in the campaign world.
Melisana is from Verdun in Minrothad (instead of Ventris on Korrin).
The Orcs are now the greenish Kara-Kara. Replace bardiches with Leiomano, polynesian wooden oars outfitted with shark teeth.
The Goblins are now Ponaturi, homebrewed polynesian goblins: they are amphibious, have bigger eyes, and are vulnerable to sunlight (-1 to rolls). The archers throw javelines instead; the bow never was much a war weapon in Polynesia due to humidity warping the bow and string.
The Goddess is Calitha Starbrow.