You start in (M2.5). Four slow bandits will attack you when you enter the big hall. Follow Leo. In the other room (M2.2) you'll be able to learn the group fighting style at last. You'll be to face 6 weak enemies at once.
Hint 14: Use the group fighting style to deal minor damage to all enemies that surround you. This style will become unbelievably powerful once you learn some advanced techniques.
Under the wall (M2.3) there's another container (a barrel again) that you can loot.
Hint 15: In The Witcher you can loot anything you want, anywhere you want. Nobody will mind you searching through their belongings just before their eyes.
When you reach the stairs (M2.4) that lead to the Laboratory, you'll see a cut-scene. You will have to learn the first sign now.