Hey there Steam people.
Just a quick update ( not a real news, that's why it's posted like this ).
If you want to check out a small preview of Chapter 4 where you can experience one event with Sabrina, do the following:
Right click your game in Steam
Click "Properties"
Select "Betas"
Then select "ch4preview"
It should download the Chapter 4 preview. If you made a savegame at the end of Chapter 3, you can immediately continue into the preview. Other savegames should also work.