what happen in chapter 19?

-They are still descending into the volcano. This time they are following a lava-like "natural staircase".

-Finally they reach the end of the chimney.

- There is an intersection where they must choose between two narrow routes.

-They keep following the path of the lava.

- They find that they have somehow left the lava path.

-THey are unsure if a mistake in direction has been made but they are also running out of water.