What happened when the Gladers attempted to approach the Griever hole?

Alby doubts their plan, and Thomas reiterates that one of them dying is better than all of them. Alby considers his words, and then charges the Grievers guarding the Cliff. The Grievers descend on him, demonstrating their cruelty. Newt and Thomas can't believe what they are seeing. Alby was so afraid of what he might encounter in the real world, he decided to end his life this way.