Najena, room 11.

[Sorn]

No, you need the key to Rathyl's cell. (If you are a small race like dwarf or wood elf, you can duck and get through the bars, skipping the first two keys easily.)

Step 1: Kill the Guard Captain to get Shiny Metal Key
Step 2: Kill BoneCracker to get Dull Bone Key
Step 3: Use Shiny Metal Key to get past door 1 to Rathyl
Step 4: Use Dull Bone Key to get past door 2 to Rathyl (right into Rathyl's room)
Step 5: Kill Rathyl to get Bloodstained Key, kill Rathyl's reincarnation just because he will attack you
Step 6: Use Bloodstained Key to reach Drelzna, kill Drelzna for Golden Crescent Key
Step 7: Use Golden Crescent Key to get to Najena

It's also useful to get the guard's keyring (from any ogre guard in case you fall into a pit trap by accident and get stuck in one of the jail cells.