From the Back of the Book:
The essential d20 System resource for rogues!
This definitive sourcebook provides players and DMs alike with everything they need to add depth and versatility to one of the most exciting character classes in the d20 System game. Path of Shadow includes:
19 new prestige classes, including the aerialist, the night hunter, and the royal assassin
13 new legendary classes, high-level character options for rogue characters of truly legendary ability, skill, and renown.
New shadow schools, such as the razorfiend tradition of drow knife-fighting
New organizational templates, including rules for membership in thieves' guilds and assassins' guilds
New feats, skill uses, equipment, weapons, magic items and spells of particular interest to rogue characters and easily integrated into any d20 System fantasy campaign
Requires the use of the Dungeons & Dragons Player's Handbook, Third Edition, published by Wizards of the Coast