The Silence of Evil
Centuries ago, a green dragon terrorized the civilized lands near its lair. As the beast grew in power, countless cult followers gathered. With the help of its worshipers, the dragon transformed into a runescribed dracolich.
The dragon and its cult grew larger and more powerful over the centuries. This, of course, led to war with the surrounding nations. After terrible battles and much loss, the cultists were slaughtered and the dragon destroyed, but its phylactery could not be found. The beast reformed, gathered cultists anew, and again was defeated. The phylactery still could not be found. This time, the powers of civilization decided not to destroy the beast, but to trap it, locking it away and setting various guards.
Recently, a divination ritual performed by someone the PCs respect revealed that great peril will arise if a creature lairing in Mount Sorrowspire (the dracolich) is not destroyed.
Pgs. 180-185