First Lever
Stand in front of the five levers and go to the second one from the right. If you mentally label the levers from left to right, one through five, it is the fourth one in the lineup. Pull this lever first.
Second Lever
Using the same mental numbering system, the second lever is actually the first one in the lineup. Pull this lever.
Third Lever
The third lever to pull is actually the fifth one in the line of levers. Pull this one to correctly follow the sequence.
Fourth Lever
According to the tombstone clue, the fourth lever you must pull is the second one over from the left. Pull this lever to continue the sequence.
Fifth Lever
The last lever you must pull to complete this puzzle is the one in the middle. Using the same mental numbering system, it is the third lever in the lineup. Pull it to unlock the room with the barrels.