I like the specificity, and there are some good parts here that give me an impression on what the story will be, but it’s also still a little too vague.

First of all, is his former teacher and wife the same person? It’s not clear, and I have no idea why it’s important that we know both, or how that death relates to the rest of the story. Challenging his demons implies he played some part in her death? If so make that clear.

Alma mater secondary school is very wordy and a little odd. Why not – former high school?

And most importantly, what is the actual movie about? Getting snowed in at a school is hardly life or death, so how does it become about survival? And is it just him stuck at a school? And why he is at the school (funeral/memorial maybe?). If the ‘demons of his past’ are not literal then I would include them. Is this a supernatural horror?

It’s a good start, but some more specifics are required.