Harry Potter and the Chamber of Secrets2002

Harry:
[reads the paper from the book taken by Hermione] "Of the many fearsome beasts that roam our land, none is more deadly than the basilisk. Capable of living for hundreds of years, instant death awaits any who meet this giant serpent's eye. Spiders flee before it." Ron, this is it. The monster in the Chamber of Secrets is a basilisk. That's why I can hear it speak. It's a snake.

Ron:
But if it kills by looking people in the eye, why is it no one's dead?

Harry:
Because no one did look it in the eye. Not directly, at least. Colin saw it through his camera. Justin– Justin must have seen the basilisk through Nearly Headless Nick. Nick got the full blast of it. But he's a ghost, he couldn't die again. And Hermione had the mirror. I bet you she was using it to look around corners in case it came along.

Ron:
And Mrs. Norris? I'm pretty sure she didn't have a camera or a mirror, Harry.

Harry:
The water. There was water on the floor that night. She only saw the basilisk's reflection. [reads again] "Spiders flee before it." It all fits!

Ron:
But how's a basilisk been getting around? A dirty, great snake. Someone would have seen it.

Harry:
Hermione's answered that too.

[Harry and Ron read the last word on paper]

Ron:
"Pipes?" It's using the plumbing!

Harry:
Remember what Aragog said about that girl 50 years ago? She died in a bathroom? What if she never left?

Ron:
Moaning Myrtle.