Dreamfall: The Longest Journey/Chapter 4: Winter

The Grubbers
Zoe has fallen into a cave. If you look around you will see two Grubbers fishing. Search for two pebbles nearby using the Focus Field and take them.

To get past the Grubbers, you have three alternatives: Take the glowing egg and continue to the ledge.

Waterwheel
With the egg in hand continue towards the big waterwheel. Move down the stairs all the way up front to the wheel and look for a new, narrow set of stairs to your right. Head up these and you'll notice a broken ladder to the left. Then walk up to the machine to the right, with the small wheel on it, focus on the upper part and place the egg there. Then turn the smaller wheel to activate the power and get the big waterwheel moving again, snatch the egg back before you leave since you'll need it later.

Head back down to the lower level just by the wheel and focus at a point where you can grab a piece of it and go with it all the way up to the top as it turns. Move forward until you get a short cut scene, then jump the gap and continue to the high ladder, climb it.

You'll reach a small ledge with a cave. Follow the stream of water until you reach what appears to be a dead end in the end of the cave. This is where the egg comes into handy, it's light will soon reveal three glowing runes. When touched they will play a tune, if played correctly (Left, Middle, Left, Right) an opening will appear.