In *Kingdom Come: Deliverance 2*, a crucial side quest involving Rosa's book is easily missed, leading to quest failure and potentially hindering romance options. This guide ensures you don't miss out.
Before Rosa requests her book, complete "Via Argentum" and begin "Taking French Leave." After resolving the Vavak situation with the Ruthard family (through force or diplomacy), speak with Rosa to learn about a secret Maleshov passage for rescuing Hans. She'll then ask you to retrieve her book, initiating "Rosa's Book." Remember to ask her specifically which book she needs before promising to find it.
This quest is only available during "Taking French Leave." Leaving Maleshov with Hans without the book results in quest failure and lost romance opportunities. Fortunately, the book is conveniently located on your way to Hans.
Upon entering Maleshov, Hans is in the tallest tower's top floor. Use the exterior stairs to enter. Inside, find another staircase and a small kitchen. Wait in the kitchen until the guards upstairs leave.
Sneak upstairs to a room with Lady Ofka. Knock her out, and collect the keys from her, the podium, and the sword from the chest. Rosa's book is a red volume in the window alcove to the right of the fireplace. Grab it, updating your objective to return it to Rosa.
While there, grab the sword from the chest in the adjacent room; you'll need two weapons for Hans and his guest later. Unlock the door on the left on the top floor to trigger a cutscene.
Following the cutscene, continue "Taking French Leave." Though Hans may initially refuse the passage, selecting the heart dialogue option (assuming you chose the heart option in Trosky) advances your romance. Sneak to the stables north of Maleshov, subduing and hiding guards. Once clear, signal Hans to ensure his safe arrival.
After the final cutscene, return to Kuttenberg City and deliver Rosa's book to Ruthard Palace, completing the quest.