Thief of Time (Discworld Series #26)

In Discworld, Time is a resource managed by the highly capable Monks of History who store it and pump it from places where it is wasted, like underwater (how much time do fish really need?) to places, like cities, where there's never enough of it.

Ironically, the construction of the world's first truly accurate clock threaten to stop Time altogether. And so begins a literal race against Time for the monk Lu Tze and his apprentice. For if the perfect clock starts ticking, Time, as we know it, will stop. And then the trouble will really begin. Subtle, sly, thought-provoking, and hilarious, Thief of Time is Terry Pratchett at his best.