From the publisher's web site:
Eleven years ago, a band of heros rose up and overthrew Kalak, the Tyrant of Tyr. High Templar Tithian took up the fallen crown of Kalak, and as his first act, granted freedom to the slaves of Tyr. For the first time in over a thousand years, the people of Tyr were allowed to govern themselves.
The Free City of Tyr became a beacon of hope, a promise that one could live free from the tyranny of the Sorcerer Kings. The hope was given fangs when the Crimson Legion, an army made up of Tyr's ex-slaves and gladiators, repelled an invading Urikite army seeking to seize control of Tyr's precious iron mines.
During the turbulence of the last decade, King Tithian disappeared, searching, some say, for an artifact of great power. In his stead, the Council of Advisors has risen to take on the mantle of leadership in the Free City. Tithian has been missing for three years, and some say that the lost king will not return. Without his leadership, many see Tyr's future as uncertain. A new threat is maneuvering to strike, not from outside, but from within the very walls of Tyr itself.
Tyrian Conspiracy is an official DS3 adventure, written for four 5th to 7th level characters. To play Tyrian Conspiracy, you will need the Dark Sun 3rd edition rules, Terrors of Athas, Terrors of the Dead Lands, and the Dark Sun Prestige Class Appendix I as well as the Player's Handbook, Dungeon Master's Guide and Monstrous Manual.