Sam Vimes is mostly happy with his wife and soon-to-be-born child and his job as Commander of the City Watch, but sometimes he misses the "good old days" back before he got the crime in the city under a semblance of control. When a knife-loving psychopath decides to go on a murdering spree, he is only too happy to join the fray. But during a rooftop chase on a stormy night something magic and odd happens: Vimes and his quarry are transported back in time 30 years. Vimes now finds himself penniless, homeless and without a single person who knows him in the messy situation of a city hovering on the edge of a city-wide riot and the supremely awkward one of meeting himself as a over-eager teenage watch trainee. Can one watchman from another time help keep people safe? and how much can he get away with before he has destroyed the timeline so badly there is no way to get back to his right place?
This book is definitely much more serious and dark than the other Discworld novel I have read (Guards! Guards!) but that isn't a bad thing. Pratchett easily glides his story between playful, introspective and action-packed moments. One moment the reader is laughing, the next brooding along with Vimes. This quick movement between styles can lead to a bit of mental whiplash, so I recommend taking a break here and there rather than trying to read it straight through.
The writing is not fancified and elaborate, but clearly conveys what the reader needs to know while staying interesting. Pratchett has a good ear for phrases that don't sound commonplace or cliche, but make perfect sense and don't require the reader to stop the story in order to try and figure out what the author was trying to say.
Tompkins County Public Library