Travel northwest to a fortress that hangs over the main road. Outside, you'll see slaves working. Head inside the canopy, walk upstairs, and on the right-hand side you'll see a desk with a diary entry ...

After saving Katya and Nastya (during The Village mission), you'll be instructed to return to the Aurora. On your way back, you'll be attacked by the tsar fish. Duke will save you. Head for the Aurora ...