The quest starts in the Shrine of Seven Stars. You need to meet with Scout Lynna at Krasarang Cove in Krasarang Wilds. There comes King Varian Wrynn, that helps you to kill 25 Horde and to find Marshall Troteman & Hilda Hornswaggle...
When you finish the quest, Varian send you to use the Flare Launcher in Krasarang Cove to signal the Alliance Fleet...
After epic intro of massive Alliance Fleet.
You found Yourself in Lion's Landing, Alliance Fortified Harbor, Where King Varian Wrynn finally see his missing son!
Watch the video if you want to see ending story of the first part This Video is huge spoiler - 7 Min : 52 Sec most of the people will be interested.