This quest can be acquired from Father Godwin, the parish preist in Uzhitz. He is concerned about rumours that the old herb-woman Gertrude has incited some Uzhitz women to witchcraft. You must speak with her to find out more.
Upon successfully persuading Gertrude, she reveals that Vera, Khuta and Zlata are the women in question. The rumours turned out to be inaccurate; Gertrude only sold a powerful and potential dangerous hallucinogenic potion to them. You must know find them in Uzhitz and discover what their intentions are.
The location of each woman is marked on the map. You can discover something of what the women intend to do with the potion by speaking to just one of them, but speaking to all will provide you with ever more detailed information about when and where to find them in the woods at night.
Once you have spoken to each woman, find them at their meeting place in the woods at midnight. The meeting place is marked on the map, so you can travel there and set the time dial to midnight. You will find them gathered just outside the woods. Follow them along the path to their meeting place.
When following the women you can choose to stay out of sight at a safe distance so that they do not detect you. Alternatively you can approach them and make your presence known, but you will have to agree to their conditions if you are to stay.
After some time a cut scene will initiate in which Henry has some of the ointment smeared on him. Now that the women perceive you as the devil who is to be bargained with, you must choose one to cavort with in their... altered form. Approach the one you chose from behind and the option to pick an easy lock will appear. Pick the lock.
In the next cut scene the women will be ambushed by two woodcutters who take them for witches. Be sure to subdue or kill the woodcutters to ensure that the women are kept safe. Alternatively you can allow the woodcutters to kill them as witches. Regardless of your choice, you will wake up the next morning with the objective to speak with the preist and tell him what happened, thereby concluding the quest. You can also speak with Gertrude, though it will not advance the quest.