Location: In the Temple of Enlightenment.
Within the Temple of Enlightenment lies an area left largely unexplored.
In order to progress through the temple then the Emerald of Despair must be obtained. By leaving from the Corridor of Timelessness through the door nearest to the Save point you will be taken outside. From here head down the stairs and right until you see a lift, near to the lift is an examination point which causes the lift in the background to rise up.
Back-tracking to the corridor and making your way up through the ruins brings you to another door to the precipice. If done correctly you will now see a lift breaching the two platforms together.
Cross the lift and proceed down the ladder, once at the bottom head to the right to encounter a cutscene involving Mack, Cooke, & Kaim. After the cutscene remove the Emerald of Despair and head back inside.