Leon's condition worsens and Chrissie reveals that it was her fault that the anti-venom was left behind. Gerry decides to head off with the sick Stanley and the other boys, leaving the girls at base camp. However, they become lost due to poor map reading, and soon another member of the group disappears into thin air.

With Mr Simmons and Melissa missing, the girls become even more scared when Chrissie starts seeing things. While Leon and the trekking party return with more strange news, Simon plots to split the group.