In Genshin Impact, The Secret of Al-Ahmar is the third quest in the Golden Slumber World Quest series. The Secret of Al-Ahmar starts as soon as you complete the previous quest, An Introduction to Indoor Archaeology, and sees you delving even deeper into the bowels of Khemenu Temple.
How to open the coffin
Once you complete An Introduction to Indoor Archaeology, follow the marker into the secret passage and ride the elevator up. Follow the marker to the entrance of King Deshrel’s Mausoleum, then go inside and defeat the enemies. Continue to the chamber at the far end, where you’ll find the coffin.
Go through the doorway in the south wall, and follow the passage around to the right. Turn right again, and you should be in a room with two closed doors and a fan on the floor on the far side. Stand on the fan, wait for it to start, and then glide up to the first floating cube. Release it, then follow it into the burial chamber until it lights up the first big pedestal.
Now go north, cross to the far corner of the chamber with the radiating turret, and collect the floating triangle. Head west and use the floating triangle to activate the glowing square on the floor. Continue along the passage, follow the Seelie (using the Four-leaf Sigil to get to the high ledge), release the floating cube, and follow it into the chamber until it lights the next large pedestal.
Go north again, and turn right at the radiating tower. Turn right again and use the Four-leaf Sigil to get up to the next floating cube. Release it, then follow it back to its large pedestal in the burial chamber.
Go south, then turn left and defeat the enemy. Use the Four-leaf Sigil to get up to the final floating square on the north side of this chamber. Follow it into the burial chamber until it opens the coffin.
How to find Benben
Follow the marker to the elevator, then ride it up. Turn right at the top, then go up some stairs. After you get knocked out cold, go through the door in front of you and help defeat the Fatui. Follow the markers a long way through tunnels and caverns until you reach a Teleport Waypoint and stop for a chat. Use the Teleport Waypoint, then drift down to the Fatui camp for some more talking, followed by more fighting. Defeat the Fatui to release Benben.
How to proceed deeper within the ruins
After the emotional reunion:
- Head south through the door and up some stairs.
- Defeat the Primal Construct, then follow the Seelie to another fight with a Primal Construct.
- Go south into the next chamber, have another fight, then rotate the two cells on the west side so that they both point at the west door.
- Go through the west door, have a fight, then put the floating triangle on the glowing square to reveal a floating cube on a pedestal. Release it and follow it a long way, releasing it several times until it finally reaches a large pedestal beside a really big door.
Now go all the way back to the chamber beneath the enormous flight of stairs and move the cell to open the door. Take the floating triangle to the glowing square beyond the door, then move that first cell back to where it was. Now you can release the floating square and follow it to its large pedestal. Go through the enormous doorway at the top of the enormous flight of stairs, then go to the marker to complete the quest.