I can say "Read the FAQ" :D
1. Save Lizard Spy
2. Help Thane (sabotage both tribes)
3. Invite Thane to the tavern
!!!! Here will be quest where you must find stolen fruits. Сhoose wisely, it will affect to good end too (2 variants).
4. Complete all dungeon and enter demon city (before go to the dungeon take some "fun" with slimes or ghosts [you need 15 curse to enter demon city]).
5. You MUST buy emblem in demon city.
6. In the tavern I don't remember when and whom (Snow or Witer) will say that Thane is awake. Chat with him, he will give you blooded bandage.
7. You'll get invitation to one of the leaders. Talk with him.
8. Go to the tample (you must have 2 emblems). And go to secret room (it will open after reading 3 books and required 1 torch).
9. Enter first picture 2 times (or 3, but third is unnecessary).
10. Check the map. Here will be new '!' mark.