Times were bleak for the Kingdom of Stormwind after the Burning Crusade. The efforts of the army continued to be dampened by Lady Katrana Prestor, who time and time again refused to send aid to the besieged province of Redridge. Stonewatch Keep fell to the Blackrock Clan of Orcs, and black drakes attacked Lakeshire.
As threats of Blackrock orcs grew, Marshal Reginald Windsor, commander of the Stormwind garrison in the Burning Steppes, sent agents to Blackrock Mountain to investigate. While traveling with the information they gathered, he was ambushed by a Dark Iron raiding party. Only one of his men, Ragged John, escaped to tell the tale. Marshal Windsor was captured and imprisoned, his hammer taken by the Emperor, Dagran Thaurissan, and the precious information seemed lost.
In late September of 619 K.C., however, Marshal Windsor was rescued by the wayward King Varian Wrynn, Broll Bearmantle, Valeera Sanguinar, and Thargas Anvilmar. He revealed to them the dark secret that he learned while stationed in the Burning Steppes: that the court of Stormwind had been infiltrated by the black dragon Onyxia, in the guise of Lady Katrana Prestor.
Returning to the capital city, the heroes of the kingdom were rallied to confront Lady Prestor in Stormwind Keep. An elite task force of the Stormwind Royal Guard marched through Stormwind alongside the king and his company with vengeance in their hearts.
Reginald Windsor accompanied the four to Stormwind and confronted her, revealing her true form within Stormwind Keep. With her plans unraveling and her disguise ruined, she incinerated Windsor and escaped to her lair after a titanic battle with the heroes of the Alliance.
Taking Anduin Llane Wrynn captive, she fled back to the safety of her lair with Varian and his entourage in pursuit. Varian, Broll, Valeera, Thargas, and Jaina Proudmoore descended into the depths of her lair to rescue Anduin and bring her to justice. In the end she was slain by Varian, and her head taken back to Stormwind to be hung from the gates.
On October 13, in the 619th year of the king's calendar, Varian Wrynn reclaimed his rightful place at the throne of the Kingdom of Stormwind.
Adapted from WowWiki.