Larian Studios Forums Divinity II The Dragon Knight Saga / Flames of Vengeance (English) Help/Tips/Tricks Stuck at mission "The murders at the Rue Lanilor".

Good day.
I am ashamed to admit i am actually seeking gaming advice for the very first time in my life.
Before we get started i have to warn people about the spoilers, no ? So if you didn't do the quest yet be warned.
In this quest there is a boss at the end. A "natural undead". He is invincible until you defeat his undead servants that are buried all around the crypt where he is. Each time you kill one of them, 1 out of 4 blue flames on the "natural undead's" tomb goes dark.
I have found two of the buried undead in that room, can't find the other two. I think i have searched every inch of that damn room and there simply aren't any more buried things to kill... what now ?
Sorry about the bad english, it's very late, and i am very tired.