This is an alternate take on the quest chain called "The Great Masquerade", which was removed when the attunement requirement for Onyxia's Lair was removed. I've changed a few minor things, like a pointless return to Marshall Maxwell to tell him you found Windsor (which completely went against the order to "Return with him alive, or with proof of his death". I also cut out the part where Marshall Windsor was going all emo in his jailcell, even though all of the dwarves guarding him were dead, and the armory was just down the hall. Note that it was King Varian Chin Wrynn who canonically did this stuff and unmasked Onyxia.