Night Watch - Terry Pratchett - Bog

"One moment Commander of the City Watch Sam Vimes is chasing a murderer across the rooftops of Ankh-Morpork. The next, he's lying in the street below, naked-and back in his own tough past thanks to a lightning strike and a group of meddling, time-manipulating monks. It's a dark Discworld that is all too familiar. Worse, the cop-killing psychopath he'd been pursuing has been transported back with him, and it's the eve of a deadly street rebellion that took a few good (and not so good) lives. Vimes is determined to do his duty- track down the murderer and change the outcome of the rebellion. By changing history he might just save some worthwhile necks, and steer a novice watchman straight-an impressionable young copper named Sam Vimes. But if he succeeds, Sam knows it could cost him the future-including the job and the family he loves. The Discworld novels can be read in any order but Night Watch is the 6th book in the City Watch series and the 29th Discworld book"--