Far be it from me to be "scandalized" by a non-rhyming sonnet

. Even free-wheeling meter doesn`t bother me, and perhaps the unquiet spirits in this sonnet need the bump-in-the-night rhythm in order to portray their insistence. If so, good. If not, there are several quite jarring lines, e.g., lines 3 and 6.
As for the chalk, I immediately thought of the lime scattered on the bodies thrown into common graves, and also how people in hiding often chalked up the days spent in hiding . . .
I think the last line is a very effective close. Kind of brought to mind Catherine banging on the window outside Heathcliff`s room.
As for the umlaut over the U, for a capital press ALT + 0220, for small, press ALT + 0252.