We were crossing a ridge when Corgan was lifted off the ground by something. "Shoot it! Shoot the tyrannosaur!" he screamed as blood streamed from the puncture wounds that had opened up in belly. I fired into the empty space above him to no effect. Then Corgan's ragged corpse dropped to the forest floor, and I was alone. Utterly alone. There was no dinosaur. There was nothing.
It is traditional for two warlike countries to each give their first-born royal prince as a hostage to each other to prevent war. One of the princes has been murdered, and the PCs have a few days to rescue the prince in the other country to save him from being executed and a bloodthirsty war from breaking out.