Take a look at the wall right from the fountain. The rectangular mechanism is being found there with the oblong groove. Run onto the wall and stick the dagger into the mechanism, falling down you will open the entrance to the left. Let go mechanism and run through newly open door to the royal kitchen.
You will be attacked by the pack of enemies. Two Specters, two Enchantresses and 10 Thralls will attack you. You need help of Power of Sands of Time, Eye of Storm especially to achieve the victory. Climb up the stairs right to the hearth after the fight. Localize relieves above your head, run vertically onto the wall and stick the dagger into the lower one. Take off upwards sinking the blade into the higher relief.
Hanging on the knife shaft turn left and run horizontally over the wall. Bounce off hard in front of the pillar to the hall center direction, and you will catch the catwalk. Climb it, move to its other end and jump to the relief on right, sticking the dagger into it. Take off to the left now, run across horizontally over the wall to the nearby horizontal bar. Clamber up it and jump on directly to the floor. Turn to the left, reach the opposite end of the floor. There is a catwalk where the rail is missing, climb the catwalk.
Jump at the end of the catwalk to the relief on the right, stick the dagger into it. Bounce off to the left, run horizontally over the wall and in front of the pillar jump to the catwalk to the hall center direction. Move to its end, take of to the relief straight ahead sticking the knife into it. Turn to the left and run horizontally over the wall. When you stamp on the tile lying in the wall near by, the door will open below you. Jump down to the ground and run through it.
Go up the stairs over the corridor, turn to the right. There is the fountain standing straight ahead, near the wall. Drink water.