Sam Vimes has spent years keeping the peace and has finally become a Duke in the sprawling city of Ankh-Morpor. A former Lance Corporal in the Night Watch, the city’s police force, Vimes itches for the days when his job entailed more than making political decisions and his days off were filled with activities more lively than waiting for his wife to give birth. Vimes gets his wish when he learns a highly intelligent killer by the name of Carcer has been cornered in part of the city. While pursuing Carcer, both Vimes and Carcer are caught in a magical storm that deposits them in the past.

So begins the chase in Terry Pratchett’s 27th installment in the Discworld series. Fans of the series will enjoy the peek into returning protagonist Sam Vimes’ past. Those readers unfamiliar with Discworld will enjoy the humor and the time-travel conundrum Vimes is faced with in the book.

In the city of his youth, Vimes finds himself charged with the task of subduing Carcer, while ensuring that history stays intact. This is made all the more difficult by the roiling rebellion that is set to explode at any moment in the city -- a city that is protected by an apathetic, and in the case of many individuals, corrupt, Night Watch. Vimes steps into the boots of his former mentor, Sergeant John Keel, and sets out to put things right so he can go home to his present-day pregnant wife.

Pratchett’s cast of characters, as usual, are colorful and memorable, from the broom-wielding monks who monitor time, to the doctor whose clientele list is almost solely made up of ladies of the night, right on down to the questionable rat-pie street vendor. Humor is sprinkled generously throughout the story, but not nearly so much as in some of the earlier books in the series. The comic footnotes Pratchett is well known for seem more sparse here.

Pratchett is at his best here when he places his characters in impossible situations and plays their inner turmoil against their actions. With Night Watch, Pratchett has refined his writing style to take on a more serious tone, though spontaneous laughter is bound to occur at certain scenes. It almost seems as though Pratchett’s body of writing has existed within a chrysalis of comedy and has metamorphosed into something more bold and dramatic. The end result is a beauty to behold.