We are coming for you and your children. We know you have made the school into a home for mutants like yourself. This is not a threat or a ransom letter because we will make sure we get rid of you and your students. There is danger on the horizon. Watch out and be afraid.
Of course the letter was unsigned and the envelope it arrived in had no return address. Charles has been stressing himself to the point of sickness, trying to find the culprit with the help of Cerebro. So far all his attempts have turned up empty.
Usually, such letters would be ignored. There are plenty of hate letters sent to the mansion when people find out that we house and educate mutants. However, this one is being treated very seriously. The ferret that was responsible for the destruction of my desk was reported to have rabies. This alone does not merit panic, but it's very suspicious that this infected creature ended up on our property in upstate New York. Then, Charles told me that Logan had found traces of gunpowder on the outskirts of the estate.
Of course, each of these components could be accounted for as mere coincidences and they may be. However, Charles is secretly preparing to evacuate the mansion by sending all the students on overnight field trips. Today he gave me the list of students I would be chaperoning in the likely case that this threat becomes more believable and credible. My accompanying adults would be Remy and Kurt.
I pray that for once Charles' intuition and Logan's nose are wrong.