After the disastrous evening meeting it seemed like the leadership group were headed for a permanent schism. However, news of a sighting of 'the beast' on the mountain top gives them a common sense of purpose and Ralph and Jack reorganize into an uneasy alliance. Dissent is not far under the surface however, and Jack's goading leads Ralph into making the fateful decision to proceed to the top of the mountain at night to find the beast. Ralph's common sense tells him to wait until it is light, but Jack's jealousy and blind ambition to be leader see him foolishly use the situation to accuse Ralph of cowardice. Fate leads him to take the final steps to the mountain top alone, and what he sees in the darkness is unclear but still terrifying to his young senses,
"I saw a thing bulge on the mountain."
"You only imagined it," said Ralph shakily, "because nothing would bulge. Not any sort of creature."
Roger spoke; they jumped because they had forgotten him.
Jack giggled and shuddered.
"Some frog. There was a noise too. A kind of 'plop' noise. Then the thing bulged." (p.150)
Jack's scant description of what is in fact a dead parachutist is hardly surprising given the fact he is seeing it in near complete darkness. The description he gives is confirmed when the three terrified boys revisit the place just moments later. This part of the plot shows again the missed opportunities the characters experience. If Ralph had followed his earlier instincts and insisted on the hunt resuming in daylight then the truth of the beast would have been uncovered, the angst the boys felt would have been relieved and poor Simon would have not lost his life.