Brothers in arms. Skellige (The Witcher 3: Wild Hunt)

it is like below somewhere

look for her at the castle

She's in the cellar, but to go to the locked door

olesenko
Look for the lock or prepromote

In short, the campaign there is only one solution to this problem: just forget about it and go to the Isle of mists without the support of the Keris, however the quest will fail