The Philosopher's Stone.

Parvati Patil said that she wouldn't come out of the girl's bathroom.

That's what's under the trap door. The Philosopher's Stone.

"The only Stone currently in existence belongs to Mr. Nicholas Flamel...

At the end of the year, the house with the most points is awarded the house cup.

This is the most direct path to the dormitories.

...who possess the predisposition...

powerful it is known as the Draught of the Living Dead.

...gives a student the right to walk about the school at night.

God, I miss the screaming.

And the points stand thus:

I knew the name sound familiar. I read it on the train that day.

It's not real, the ceiling. It's just bewitched to look like the night sky.

...that the third-floor corridor on the right hand side is out of bounds...

She was quite an extraordinary witch, but she did like to experiment...

The Sorting Ceremony will begin momentarily.

Who's the one wizard Voldemort always feared?

As for monkshood and wolfsbane, they are the same plant, which also goes by the name of aconite.

The swish and flick. Good. Oh, and enunciate.

I thought you said the four of us.