Actually, this is where I'm stuck. Can you give me a hint?
I've gone through the middle corridor, and come up to the mirror. Desann laughs, then I can see him in the mirror, then he turns around and runs back.
Can't get through the fire in the corridor on the left.
The corridor on the right seems to be a dead end. I've tried jumping over the chasm. Nothing. I'm pretty sure that's the way he went though.