Christmas in the Shadows by Christy Barritt

Tex Thrasher has no idea why, after twelve years, his former foster father asked him to come back to his hometown for Christmas. When he returns, the last thing the former special ops soldier expects to find is his high school girlfriend rummaging around the office in his old house.
High school teacher Chelsea Lennox suspects her neighbor—the high school football coach—is up to something nefarious when she notices unusual activity next door during the night. Fearing the man is putting her students in danger, Chelsea sets out to uncover the truth. But someone thinks she knows more than she should, and the threats against her escalate.

With Christmas fast approaching and lives on the line, Tex and Chelsea team up to bring the culprits out of the shadows and prevent further danger and deaths. But as old feelings resurface, they have to decide if they can trust each other—and Tex’s foster father—before it’s too late.