Basically it's the climax of the entire story
Everyone is fighting to protect the Singularity
Meanwhile Will and Illy go to try to fix its containment area
Illy is supposed to pull Will out when he's done
But the Singularity pulses so powerfully that Illy gets vaporized
And the Singularity, unfixed, collapses in on itself
It then creates the island that Hero wakes up on