From the introduction: To Catch a Thief is an introductory adventure for Age of Steel, taking players and gamemasters alike on a short trip through Dar-el, the City of Sapphires; the infamous city of intrigue on the northern coast of the Free Nations. Hired to find a stolen artefact, the player characters find themselves immersed in the seedy underworld of the jewel of Kijani. To Catch a Thief is a standard level adventure for between three and five players. Five pre-made characters which players can choose from are included in this supplement.