Story related - can't be missed.
When you wake up at the start of the level, collect the grappling hook on the crates in front of you. Make your way forward through a gate and then start descending the shaft. You can fall to your death if you are not careful here but the path is pretty straight-forward. At the bottom of the shaft, head up the stairs and pull the lever in the Dominus Illuminatio Mea room. This opens up a map in front of you and a gate in the previous room. Head back there and go through the gate. You should see a gold shiny plate underneath a torch in front of you. Collect it and then head left down the tunnel to collect 3 more at various places. You'll need to swing via the hooks on the ceiling to cross the gaps. After you have collected all 4 plates, return to the map room and place a plate on each of the 4 podiums around the map. this will end the episode and the achievement will unlock right away.