There are 9 pressure plates and 9 tombstones with names near them.
The plates should be stepped on in following order:

• Ronan Great
  
• Brian Blessed
  
• Ronan II Gifted
  
• Logan Beloved
  
• Connor Charming
  
• Erwan Builder
  
• Brian II Merry
  
• Ronan III Patient
  
• Lea Peacemaker

The chest with loot will pop-up in the middle of the room.