A Discworld novel wherein Commander Vimes chases a murderous thief into the past and endured a You Will Be Beethoven wherein he must become his own mentor.
Or, alternatively, Terry Pratchett's take on Les Misérables.
http://tvtropes.org/pmwiki/pmwiki.php/Laconic/NightWatchDiscworld
FollowingLaconic / Night Watch (Discworld)
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