Missing People!

The school's board and previous chancellor disappeared during the term break before our first term started. They were all together, having a meeting that wasn't part of the normal schedule. They were quickly summoned together to meet over the summer, but were never seen. When professors returned, near the end of the break, there was no evidence of scuffle, no strong magical traces. They *arrived* at the school; various people saw them arrive...

The *weirder* thing ... (our narrator started, but trailed off...)

Also, during the welcome address, the Headmaster alluded to the previous headmaster and other faculty being... "consumed".. *And* he said, "No one gets lost… for more than a year.  And they always make it back to their houses.  On the same day?" (that year?? The next year??? How can they be lost for a year and be back the same day?)

Anyway, now MIM IS MISSING! Wait, no, false alarm. She's back. But she has a letter from Derek that he doesn't remember writing? His memory is fine and the letter is real, but seems, to Professor Helios Killjoy (History of Magic), like it "doesn't quite fit." Very strange.