Upon moving to Bixby, Oklahoma, fifteen-year-old Jessica Day learns that she is one of a group of people who have special abilities that help them fight ancient creatures living in an hour hidden at midnight; creatures that seem determined to destroy Jess.

The Midnighters are baffled when the blue time suddenly occurs in the middle of the day. They soon discover that the walls between the secret hour and real time are crumbling, and, unless they can stop it, the dark creatures will have a chance to feed after centuries of waiting.