Unlike most Discworld novels,
Night Watch has a far more serious tone. This often occurs at the expense of humor, and frequently goes as far as being sad or tragic. It was a risky experiment on Pratchett's part, and while it largely succeeds, it's not quite up to the level of his best work.
We follow Sam Vimes, the leader of the City Watch (Ankh-Morpork's police force), and now a Duke who is second in power only to Lord Vetinari himself. However, while chasing after dangerous criminal Carcer, an explosion near the Wizard's University sends him back in time roughly thirty years.
He comes upon Ankh-Morpork when it is being ruled by the evil despot Windor, the Night Watch is a mixture of incompetent and corrupt, and revolution is brewing. Not only must he make sure nothing goes horribly wrong at this volatile point in history, but he also has to contend with arch-nemesis Carcer, who is even more dangerous in the past.
Make no mistake; this is still an engrossing, fun read, with plenty of action, Pratchett's usual witty observations, and excellent characters. However, I struggled with the lack of comedy. It's the main ingredient in the Discworld novels, for all the other things Pratchett does well.
At times, the book still succeeds even without humor. Although Pratchett only lightly touches upon politics, he does so effectively. At one point, it's mentioned that the sadistic Captain Swing's decision to ban citizens from having weapons only had the effect of massively aiding criminals (who, by definition, don't follow such laws!), while punishing decent, law-abiding folk.
Mostly though, Pratchett confines his remarks to human nature. And at its best, they are intelligent thoughts about the state of mankind. I particularly liked the following quote;
it wasn't that you had the wrong kind of government, which was obvious, but that you had the wrong kind of people. However, once we are done with the philosophical ruminations, we get to the events of Vimes' adventures in the past. While exciting, without the seasoning of humor, they're a little too simplistic and predictable. This is accentuated by there being no thrills or surprises in the conclusion of
Night Watch, unlike the best Discworld novels.
Indeed, we are presented with a slightly sanctimonious ending that I saw coming from a mile away, and don't particularly care for.
Overall, it's a fun read worth checking out for any fan of Pratchett. However, don't expect as much humor or imagination, although the more serious approach occasionally works.