This is the forum for helping you out if you're stuck or if you want to discuss the nitty gritty details of the dungeons within Mount Grimrock. Warning: forum contains spoilers!
im gusssing one of the keys u missed is from the haunted halls. There is a presure plate n there that opens a wall on the other side - u have to lure those skeleton leginarries onto the pressure plate while u then book it to the open wall - 1 key is in there.