I guess there's supposed to a lever behind the throne to locate the assassin but all I have is a bunch of thorns or twigs where the lever is supposed to be. The quest arrow is showing behind the "wall". Anyone know what I'm missing here or is this a bug? Is there a way to get around this?

UESP says:

• The switch which lowers the stone wall to reveal the Assassin of Old will not appear on the wall behind the throne if the player has not received Olava's reading.

if you are on pc try tcl to walk through the wall.

That's interesting but don't you need her reading to get the quest marker pointing to the assassin in the first place?

*shrug*

yep, I did receive her reading already and I'm using Xbox.

Huh. Probably have to reload then.

give me a few minutes, i'll go there and pinpoint exactly where the lever should be.

so it should be to the left of the door behind the throne - its a round lever.

I had the same problem, and found that it's actually a well hidden pull switch along the wall.

well now, don't I feel silly
yep, your right, it's on the wall and not DIRECTLY behind the throne. I don't know why I thought that. Thank-you to everyone who helped me out with this.

lol. glad you found it!