A crisis looms when Leon is bitten by a snake, and he reacts badly to the venom. Can the series of strange encounters in the inhospitable Paramundi region be the evidence of alien activity the group has been seeking?

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.