From the introduction:
The blasted ruins of the Mournland—a lasting reminder of the devastation of the Last War—conceal many weapons from that conflict. Thankfully, the locations many of these weapons have been lost from memory, but that is not true of all of them.
...
"Ten days ago, you were hired by Tophran Damilek, one of Sharn’s wealthiest citizens, to retrieve a particular Eberron dragonshard. Damilek supplied you with a map to the dragonshard’s location—an ancient vault hidden deep in the Mournland, the blasted reminder of the Last War—and warned you that the shard would likely be protected by powerful wards and guardians.
"Now the elemental-powered airship you chartered nears the point where it will descend low enough for you to disembark and complete the remaining trek to the vault on foot. You’ve gathered up your armor, weapons, and gear, awaiting the captain’s call."