From the Wizards of the Coast website:
Decades ago, a wizard named Sylvene came to the Sword Coast from another plane of existence called Ravnica. While exploring Waterdeep and nearby lands, she met and fell in love with the father of her child. She built a refuge for them in a small demiplane of her own creation, but eventually she went home to Ravnica with her infant son and never returned.
Now her grandson seeks to recover relics of her power by exploring Sylvene's history in the Realms—and he doesn't care who he hurts along the way. The consequences of his careless pillaging already ripple out to impact others.
This Dungeons & Dragons adventure is written to suit four to six characters of 8th level. With this text and the core D&D manuals, you have everything you need to play.