The Triangle sourcebook provides a detailed setting centered on of a wedge of relatively lawless space situated between The Federation, The Romulan Star Empire, and the Klingon Empire in the FASA Star Trek universe. The manual offers a map of the sector and details for 120 stars, their planets, the political forces at play, and mercantile information for playing freelance/mercantile player characters in this space.
This supplement is best used with FASA's Trader Captains and Merchant Princes Expansion. Play may be enhanced by, but does not require familiarity with the major race supplements (The Klingons, The Orions, The Romulans, The Federation). An optional adventure campaign is provided in a companion product, "The Triangle Campaign."