Timekeeper: The Timekeeper Trilogy, Book 1 (Hardcover) by Tara Sim

Two o'clock was missing.

In an alternate Victorian world controlled by clock towers, a damaged clock can fracture time - and a destroyed one can stop it completely.

It's a truth that 17-year-old clock mechanic Danny Hart knows all too well; his father has been trapped in a Stopped town east of London for three years. Though Danny is a prodigy who can repair not only clockwork but the very fabric of time, his fixation with staging a rescue is quickly becoming a concern to his superiors. And so they assign him to Enfield, a town where the tower seems to be forever plagued with problems.

Danny's new apprentice both annoys and intrigues him, and though the boy is eager to work, he maintains a secretive distance. Danny soon discovers why: He is the tower's clock spirit, a mythical being that oversees Enfield's time. Though the boys are drawn together by their loneliness, Danny knows falling in love with a clock spirit is forbidden and means risking everything he's fought to achieve.