After obtaining the book, climb down the ladder on the left.
After coming down, pick up the item on the right, then continue sliding down.
After coming down, keep moving forward, defeat the enemies here, and take the left path at the fork.
Head forward to find a purple item. Pick it up and continue down the slope.
At the end of the path, you'll find the book [Jianghu Strange Tales Clue #14: List of Atonement]. This book is the quest objective "List of Atonement."
