This is the next quest in Onyxia chain after "Jail Break!" and "Stormwind Rendezvous"
In this quest player should follow and protect Reginald Windsor and at the end, Lady Prestor should transform into Onyxia and kill Reginald Windsor.
But there are no script for this quest :(
And this quest can not be completed
p.s Quest "Stormwind Rendezvous" is broken too
In this quest player should speak with Squire Rowe and then Reginald Windsor appears, complete quest "Stormwind Rendezvous" and start escort-quest "The Great Masquerade"