In a world where vampirism is a known and highly regulated medical condition, Caleb is a new and unwilling inductee. Haunted by loneliness and the ethical horror of his new existence, he takes a job that is a quiet form of self-torture: a night-shift technician at a 24-hour blood donation clinic. His plan is simple: surround himself with a safe, humane source of sustenance to study, and keep his head down, forever.

He expects only the low hum of refrigerators and the constant, silent battle for control. He doesn't expect Dr. Ben Carter.

Ben is a brilliant, funny, and relentlessly human hematologist who works late, fueled by coffee and an infectious passion for his research. He's immediately intrigued by the quiet, melancholic new tech who knows more about blood than any Level 1 technician should.

Under the sterile fluorescent lights, an easy friendship sparks into an attraction that is as powerful as it is forbidden. For Caleb, whose primary rule is to protect humans from his world, falling for one—especially a man who works with blood—is his greatest taboo. Their connection is governed by an unspoken "sunset clause": it can only exist in the stolen hours between dusk and dawn. But as their orbits draw closer, they soon find that the most dangerous secrets are not the ones kept in files, but the ones shared between two hearts in the quiet of the midnight shift.