From the introduction:
At long last, the PCs have reached the bottom of Dragon’s Delve, the court of, and home to, Metterak the Dragon Prince. For two thousand years the mighty red dragon has laired here, building an army of servants and slaves to serve his dreams of power. However, Metterak has never trusted more than a handful of his agents to remain close to him, and suffers the paranoia common to his kind as regards protecting his treasure hoard. Metterak originally came to these caves because their indigo iron-laced walls would keep his valuables safe from plane-traveling thieves. In the centuries that have passed since, he has grown to be arguably the most powerful dragon alive (perhaps ever to have lived). He has spared no effort in making his lair a place of comfort for himself, but still prefers to settle in his main chamber alone, sitting on his pile of gold, gems, and relics, plotting to ascend to godhood.