During the party bring a drink to Razelan to create a distraction. Then head through the door with melborn. after you gather your things, and he locks the door behind you, feel free to either sneak passt, or kill the two guards and the mage. head up the stairs and go out the door that says to skyrim. kill all the guards in the inner courtyard, then head into Elenwen's Solar,kill all the guards in here, and ind the chest with some information in it (will be marked on your map) then, head down the stairs and through the dungeon. It is easy to sneak through here if you wish, so sneaky sneaky down the stairs, wait for the guard to pass (or kill him) and get the info from the chest. Then, open the cell door and talk to Etienne Rarnis. After your done, the guards will show up and tell you they are onto you and they will kill Melborn. kill the guards and take the key from them, using one to unlock the trap door into the reeking caves. There is a troll rather close to you when you enter so be ready. kill the troll and head out the exit, then meet back up with Delphine back in riverwood.
Diplomatic Immunity - 20G