1.) In the first scene, find the potion and drink the wounded gribler, he will give out the sword.
2.) Kill the guard or steal the key and get on the scene the prison outside.
3.) There, find a nut and feed the captive gribler, ask him to raise a riot.
4.) Open all cameras and kill all guards
5.) Having come to the sewer, you need to find a stone and throw a stone into the web.