What the achievement asks
Collect nine books in the post-storm Forbidden Reach. Account-wide.
Six of them lie in the world. The other three are not on the island at all.
The six you can fly to
| Book | Coordinates | Where exactly | Video |
|---|---|---|---|
| The Burden of Lapisagos | 48.19 73.66 | In the War Creche. Cave entrance at 51.91 59.63 | Watch |
| A Song of the Depths | 71.04 67.26 | Near the naga | Watch |
| Lost Expedition Notes | 57.45 63.42 | Middle of the tower | Watch |
| A Soldier's Journal | 64.78 34.41 | In a cave, entrance at 60.31 38.60 | Watch |
| Return of the Nightsquall | 34.93 8.91 | On the ship | Watch |
| Words of the Wyrmslayer | 61.55 33.78 | Top of the tower | Watch |
The three that are not outdoors
Living Book, Opera of the Aspects and The Old Gods and the Ordering of Azeroth (Annotated) sit in random rooms inside the Zskera Vaults. They turn up while you are opening doors, not while you are flying the island.
If you have swept the whole island and are stuck at six of nine, stop searching outdoors. Those three come from vault runs.
That ties this achievement to Door Buster, which wants 150 doors opened, and Every Door, Everywhere, All At Once, which wants every door of a single vault. Keep the book list open while you run them.
Two are underground
The Burden of Lapisagos is in the War Creche, reached through the cave at 51.91 59.63. A Soldier's Journal is in a cave whose entrance is at 60.31 38.60, a good way from the book itself.
Its twin works the same way
While We Were Sleeping is the same idea with a different list, and three of its books are likewise only found inside the vaults. Collect both on the same runs.
Where it fits
One of eleven under You Know How to Reach Me, which grants the title The Forbidden and is part of A World Awoken.