Harry Potter and the Half-Blood Prince
Chapter 26 - The Cave
Dumbledore and Harry arrive at a cave. The headmaster is sure that the Horcrux is hidden at this place, because he feels the magic of the surroundings. Harry follows Dumbledore into the inner cave. When they arrive at a lake which is inside the cave, Harry backs off. There are dead bodies in it.
Fortunately they find a boat with which they cross to the island in the middle of the lake where the Horcrux must be hidden.
When they arrive at the isle they worry about a green liquid which seems to be very dangerous. Dumbledore wants Harry to make him drink the potion completely, no matter what happens. After some cups of the liquid, Dumbledore′s respiration weakens and Harry gets some water from the lake and is gripped by a corpse′s hand. Harry fights instinctively. Suddenly the cave is filled with fire, which comes from Dumbledore and Harry′s headmaster takes the wanted thing from the basin and orders Harry to go back to the boat. Luckily their escape isn′t noticed by the Inferi and both of them leave the cave without any further incident.