A warm breeze brushed across the sands of the Great Fire Desert, stirring the golden grains slightly. The movement caused by the wind was about the only movement to be seen- heat lay over everything like a thick, invisible blanket.
Beneath the burning sands, in a cool, dim chamber, an amazing discovery was being made.
"Professor Hassan!" a slim girl called.
"Yes, Ophelie?" A tall man appeared from behind a large boat. He was Professor Hassan, a professor who had devoted his life to finding out more about ancient cultures.
"I just found a false wall," Ophelie said.
"Really? How?" Professor Hassan hurried around the edge of the boat as he spoke.
"I was tracing some of the hieroglyphs on the wall, and I must have pressed some hidden trigger," Ophelie explained. "The room isn't very big, though."
Professor Hassan hurried around the edge of the boat. "Really? How?"
And, I'm a total sucker for trapdoors and hidden rooms.
I'm a bit confused about whose point of view this scene is in. It seems as if a narrator is talking at the beginning: "an amazing discovery was being made" and "a slim girl called". If it's not a narrator, then those elements might be confusing. Since it's such a short excerpt, it's hard to tell if it's really an issue, though.
"I just found a false wall," Ophelie said.--You could drop the dialog tag here. It's pretty clear who's speaking without it.
Also, I agree with Stacia that the last line of dialog for the professor is too wordy. Try breaking it up a bit. I also like her suggestion about putting the Prof's action before the "Really?" It adds more urgency and breaks up the dialog. Also, it might be nice if you describe the boat. Since I assume this is a dig of some sort, this is a great place to give a clue about what they're working on, as well as adding some texture to the scene.