The ruin that birthed a society; the Life and Times of a city in the throes of death.
Triastu. The City of the Three. The Hallowed City. Triastu is the holy city of Trianarianism, and is the home of the Trirex. Many have paid homage to it, and many have gone on pilgrimages to it, and have marveled in its beauty.
Sid and Jir were childhood friends growing up in the same town on the ocean. Both creative geniuses, both with the need to be better than the other. Many will tell you that this friendship created their genius while others realized, in hindsight, that it spelled the lands doom.
The PCs are accosted in a major city containing at least one famous fortuneteller / prophet of the future. They are informed that their as-yet-unborn child will (insert terrible evil), and that, although they are very sorry, the PC must be executed to keep this from happening.