Walkthrough

Alone in a pit with zombies under a spider, but I think that's number 0, you already have it; the rest are lying around in quite noticeable places in the following halls. If you climb the chain above the spider statue in the vicinity, (I think I went further through the top), you'll get to the next hall, there's a stone and again not a very noticeable passage to the next hall. After going through them and collecting the stones along the way, you'll go in a circle and return to the spider.