Tulan of the Isles describes the city of Tulan, which lies in the same area as the city of Carse. Unlike Carse, which is a free port city, Tulan is ruled by the Baron of Carse. The book provides detailed information about the buildings of the city and their inhabitants, as well as background on the local politics, and provides a fold-out map of the town and blueprints of some of the buildings. The lands immediately outside the city are also described, including the nearby village of Hoxley.

The book also describes what a typical party of adventurers would do upon entering the city, and provides a random encounter table with basic story hooks.