From the publisher's website:
The Spell Treasury contains hundreds of spells just waiting to be introduced into an existing campaign. Obviously, one can just add the spells as "now available," but that doesn’t seem very heroic somehow. The purpose of this adventure is to illustrate some possible ways to bring the new spells into an existing campaign. It shows the spells, adventure ideas, and research methods from the book - well, as many as we could cram in - being used in a game setting. Not all spell effects are available for players to use. Some are there to provide variety and challenges to the players, while others are there to add atmosphere and flavor to the story being told. DMs can use the adventure as written or use it for its tips on how to put the resources in the Spell Treasury to good use.
This short adventure, "The Lost," is a free web enhancement by Jeffery A. Dobberpuhl for the Arcana Evolved Spell Treasury, which he co-authored. While you don’t need the Spell Treasury to use "The Lost," many of the spells referenced here come from that supplement. The scenario is suitable for a party of six 7th-level characters in any area of the Diamond Throne setting or any other Monte Cook’s Arcana Evolved or d20 System fantasy campaign.