This Lost Book is found in a building right next to the Harbor Camp. This is a Restricted Area on the Northern coast of Karkh, in the Sharqiyah district. It’ll be North-North-East of the district’s Viewpoint on the Al-Me’dhana Al-’Ateeqa.

The building you’re looking for is on the mouth of the river to the West of the Harbor Camp. The Lost Book is on the second floor, but of course you can’t just walk inside through the front door!

Head for the Eastern side of the building and locate the blue curtained hiding spot on the corner. Jump onto it from the side so you can then climb up onto a wooden platform one storey up.

Up here you’ll find a window that you can peer inside through. Take out a Throwing Knife and use it to unbar the window on the opposite side of the room. The bar is kinda tough to spot, but you can use Eagle Vision to pick it out more easily.

With it unlocked, get over to that window from the Western side of the building and climb through it. You’ll find the Lost Book here in the corner, on a table filled with scrolls.