The Eventide Mask allows you to sneak into Vernworth Castle without attracting as much attention.
She’ll lead you a short distance to the entrance of theGuardhouse.
Head up the stairs and into the Guardhouse.

At the top of the staircase, turn left.
The first door on your left contains a chest which you may as well open since you’re here.
The second door on your left houses aTorn Letteritem on the table.

Thankfully, whatever your previous actions in that quest, he’ll help you by distracting the guards outside.
After the cutscene, exit the roomvia the windowbehind you, and jump down from the roof.
You’ll also get 6,500g and a Wakestone as a reward.

But strap in, because the next quest also involves sneaking into Vernworth Castle.

