Here's everything we know about the Calendar Killer in Shift at Midnight. Who is the Calendar Killer in Shift at Midnight? ​The message makes it sound like you're about to come face to face with the Calendar Killer during your next shift. ​Does the Calendar Killer Exist in Shift at Midnight? Subscribe to the newsletter for Shift at Midnight lore Curious for more answers about the Calendar Killer and other Shift at Midnight mysteries?