Brat Farrar

This classic mystery from 1949 follows few of the rules set down by Tey's peers (Christie, Sayers, Marsh) of the "Golden Age" of British crime writing. To begin with, there's no body, and no detective. What there is, is an imposter (the Brat of the title), who turns out to be perhaps the most likable fellow in a rather likable (if quirky) collection of minor British aristocrats. Tey (quite a mysterious character herself) liked to break the rules, and this tale does turn the usual crime story inside-out, but for me it's the wit and the characters, as much as the crime, that make it a classic.