What is the name of the WoW quest that ends with the pretty song?

[Biggirl]

It's on the horde side and I don't usually play horde. You turn it in in the Undercity and ghosts or some such bust out in harmony. I'd like to show it to someone. If anyone knows the name of the quest, I'd be much obliged. Or, even better, a youtube of it.

[Palooka]

Lament of the Highborne is either the song or the quest, but ultimately what you're looking for.

[Jragon]

It's the name of both.

[Biggirl]

Thank you both!

Here she is singing it. The real woman, not Silvanas: www.youtube.com/watch?v=cG3iUdhSlLU