The Gospel According to Sam Spade
One of my all-time-favorite motives for the hero of a mystery novel dates back to 1930.
Sam Spade, in THE MALTESE FALCON, decides he has to investigate — and avenge — the murder of his partner, Miles Archer. Why? Because the guy was his partner, and when your partner gets killed, you’re supposed to do something about it.
It didn’t matter that Sam didn’t like Miles and Miles didn’t like Sam. It didn’t matter that Sam was having an affair with Miles’ wife, Iva, behind Miles’ back. It didn’t matter that, with Miles dead, Iva’s not looking so good to Sam any more.
At best, Sam Spade could be called morally adrift. At worst, a shit-heel.
But still. When a guy’s partner gets killed, you’re supposed to do something about it.
I love the moral ambiguity but steadfast rightness of that motivation.