Once inside grounds, and middle room with locked doors,then what? Where do I find the keys? Is there another door? AUK!!

There is another building with a pair of open double doors. Inside is a lever that loads the actual dungeon area.

I have the same problem I think. I've recovered all the necessary components I need to finish this quest, but cannot access the rooms in this area. To whit, I cannot unlock the 2 doors imediately inside the main building in the castle with the shallow pool of water. I cannot pick the lock on one door, another is already unlocked, but two remian unaccessible. I have searched the whole map and still cannot find a key that opens these doors. Can anyone direct me to the exact area they picked up what should be identified as the Rune Key? I have alreayd used the ?Strange Key? Elsewhere, so i do not mean that key. This unlocks the two locked doors in the 'pool' room. I'd say more but don't want to give any more spoilers than necessary

Well, when you enter castle (water pool room), one doors are open, they lead to room with D'Soto spirit, behind next doors is room with demonic imps and KEY hanging on wall in holder. Graphic looks similar to lock but I click it and I got key for doors in pool room. One doors in pool are are pickable with lvl 5 lock, I used lvl 3 lockpick and made it on first try. Inside is chest with loot. Not sure, maybe here you can get sword Robinsword or you get it from spirit in barracks (warrior quest). To get to Barracks, use key you found on one doors next to pickable ones, first room has undead smith and some quest stuff (strange skeleton closed in jail, broken lever, usable anvil), next doors lead to barracks, be rdy to find plenty of skeletons, some guardian spirits (not sure right name) and finally warrior quest spirit. He didn't use magic in just swinging slowly sword. He has plenty health tho. Dispell undead is best attack spell here. Many undead. all in one spot. That'a all I saw in castle, I returned to sell stuff. SO robinsword is on spirit or locked doors' chest