Given away as part of WotC's "Game Day 2004" promotion.
From the introduction of the module...
This adventure is designed as an introduction to the world of Eberron and is intended for a party of four 1st-level characters. Adjust encounters accordingly for groups with fewer or greater numbers.
This adventure takes place in Sharn, the City of Towers. It begins, as many incidents in the City of Towers do, with a corpse. A warforged assassin, a mysterious blank book, and an offer from a House Cannith heir leads the adventurers into the depths of Sharn - eventually to an ancient ruin dating back to before the creation of the Kingdom of Galifar.