Begin Chapter 1 at the Sanotorium where you will meet Fenthick and Desther again. Fenthick will inform you that Aribeth is waiting for you at the Halls of Justice. Now you can continue talking to Fenthick or you can go to her immediately.
Aribeth enlists your help in regaining the Waterdavian creatures that seem to have scattered around the city of Neverwinter. She gives you the Stone of Recall as an aid and the hint to first head to the Peninsula District and find out what happened there.
Note that interactions with NPCs will affect your alignment. In this manner, you can actually shift alignments during the game based on how you'll react to situations around you.
So what now? I suggest you walk around the City Core first, stock up on items, potions and maybe even get a henchman. It's also helpful to talk to NPCs you never know when they could give you a task in exchange for something. (Note, the sidequests for Chapter 1 will be categorized according where they can be accessed with a guide on how to solve them too, the Main Quest of the Waterdavian's and the mysterious notes will be given separate articles.)