Visions Across the Veil

Narcissa expected to celebrate her wedding anniversary in quiet contemplation, thinking about her long dead husband. Instead he travels across the veil to see her and give her a dire warning. His warning changes everything but Narcissa doesn't know if she will be able to do what needs to be done before time runs out.

This is book 3.5 of the night World Series

Visions across the Veil is a Night World Novella that takes place before Lady of the Dead but does make some mention of other books in the series.