"This morning, Commander Vimes of the City Watch had it all. He was a Duke. He was rich. He was respected. He had a silver cigar case. He was about to become a father. This morning he thought longingly about the good old days. Tonight, he's in them."

In Night Watch, Terry Pratchett takes us back to a time when the Watch was corrupt, the Patrician (Winder, at that time) was more than a bit off his rocker, and a young Lance Constable Sam Vimes was in serious danger of having his naiveté land him in a cold plot of ground in the cemetery of Small Gods. Fred Colon is just a corporal, Vetinari is still a student, and unsuccessful street vendor Mr. Dibbler hasn't yet earned his famous nickname (though the origin of the nickname is revealed). Pratchett handles time travel and the difficulties of temporal paradoxes as only he can.

Attempting to apprehend Carcer, a psychotic cop-killer, Vimes and his prey are both hurled back in time when lightning strikes the Library at Unseen University, where they happen to be scuffling. While the Monks of History try to set the time lines back in order, Sam assumes the role of John Keel, the Sergeant at Arms of the Watch house at Treacle Mine Road. As Keel, Vimes takes his younger self under his wing and begins teaching him the skills and habits that he will need to survive the mean streets of Ankh-Morpork. And those skills are soon put to the test.

Fed up with the increasingly unstable Patrician Winder and the corruption that is rampant in the government, the citizens of the city are ready for a revolution. The older Vimes knows the outcome of this situation, and tries to prevent the slaughter that is to come. With the help of his younger self, Corporal Colon, an odorous street urchin named Nobby Nobbs, and the men of the Treacle Mine Road house, Vimes tries to clean up the Watch, stop the Unmentionables (Winders secret police force), soothe a rebellious citizenry, and search for the escaped Carcer. If he fails in any of these, the world he knew (as his past, or young Sam's future) will never happen.

The book moves at a good pace and has enough action and adventure to hold your interest until the very end. The dark undercurrent is no match for Pratchett's wonderfully warped sense of humor, which shines through yet again and makes for a very enjoyable read. Disworld fans will definitely want to add this book to their collection.