Omorli Villa (Location)
A stately manor in Memphis. You'll pass through here during the Dream of Ashes side quest.
The treasure here can be pinpointed in the middle of the house. Though it can be tricky to tell from above, it's on the ground floor.
If you want to claim the treasure without killing (which you should- these guys are just houseguards), approach from the bluff to the east.
There's one guard who's always moving between the ground floor and the north balcony. Wait until he takes up the balcony position, then drop behind and enter the house.
Take the stairs down and locate the red chest, against a central pillar.
Looting it ends the mission, though you may need to flee immediately afterward.