You decide that stealing the book is too dangerous. A wizard could have magical protections and invincible guardians. The paths to the mountains are dangerous and full of terrible creatures, but that is still better than facing the power of a high-level wizard in his own tower.

You inform the wizard about your decision, and he tells you that, if you want, he knows a group of rogues who can help you with that quest.
They don't have much experience, but they can help you with traps, locks, and stealth.

You have to decide...
If you accept the help of the rogues, you could be betrayed and killed in the ruins, and no one would ever find out the truth...
But going alone can also be dangerous. You could be ambushed at night while no one is guarding the camp.