What a Tangled Web...
More than a hundred years ago, clans of Dwarves and Gnomes made an agreement known as the Phandelver's Pact, by which they would share a rich mine in a wondrous cavern known as Wave Echo Cave. In addition to its mineral wealth, the mine contained great magical power.
Human spell casters allied themselves with the Dwarves and Gnomes to channel and bind the energy into a great forge (called the Forge of Spells), where magic items could be crafted. Times were good, and nearby human town of Phandalin prospered as well. But disaster struck when Orcs swept through the North and laid waste to all in their path.
A powerful force of Orcs reinforce by evil mercenary wizards attacked Wave Echo Cave to seize it's riches and magic treasures. Human wizards fought alongside their Dwarf and Gnome allies to defend the Forge of Spells, and the ensuing spell battle destroyed much of the cavern. Few survived the cave-ins and tremors, and the location of Wave Echo Cave was lost.
For centuries, rumors of buried riches have attracted treasure seekers and opportunists to the area around Phandalin, but no one has ever succeeded in locating the lost mine, In recent years, people have resettled the area. Phandalin is now a rough-and-tumble frontier town. More important, the Rockseeker brothers—a trio of Dwarves— have discovered the entrance to Wave Echo Cave, and they intend to reopen the mines.
Unfortunately for the Rockseekers, they are not the only ones interested in Wave Echo Cave. A mysterious villain known as the Black Spider controls the network of bandit gangs and Goblin tribes in the area and his agents have followed the Rockseekers to their prize. Now the Black Spider wants Wave Echo Cave for himself, and he is taking steps to makes ure no one else knows where it is.