This is good, but incomplete. It's McGonagall to a point, though. She has a bad habit of not wanting to listen when children try to tell her things, which, like the Stone debacle, can end in disaster.
Where the bloody hell was Dumbles through all this anyway? He had to know something wasn't right...but then again, he knew something wasn't right in canon and still insisted on doing things his way.
"To hell with them all." Will Harry run or will he do himself in? I guess we'll never know because you ended this story too abruptly.