where to find the key to the secret room in the sewers ? (Gothic 2)

It gives the person who holds you to Her (name not remember).
You just need to talk to him about the test cracker, well, or something like that.

Clery supposedly guards the treasure of the Guild---I do not remember he gave or not

Kill Attila, well, or peacefully pass. Next, go to the sewers. There you on the road to Kasia will be waiting for people. He is the key character.

p.s.
In the trunk you will find an amulet +10 p. and a potion of dexterity.
+ bow bospera.

this Jasper which leads you to her I no che gave

and inwhat Chapter he should give the key ?

So you're in a Guild entered? ;D

of course

Oh..this is..
In tretia Chapter! From Jasper you receive about the dialogue what is behind a closed door?.

Tomorrow pereproydu this episode and say what's what.

Pro key.
I do remember that in the third. The second Ramirez asks you to bring him a Sextant. I always have a notebook entry. As the Gothic often play notes and episodes - sea. Here is the code:
(P-P-P-L-P-P-P-L-P-L-P-L-P-P-L-L-L-P-P-L)

The most valuable thing there - a potion of agility. Bow bospera in another chest. Not knowing code, without dexterity 80-100 is better not to try. Picks a bunch of bleach)

There is a full guide on YouTube -