“Secret societies, camorras, mafias, et al., have no place in a detective story. To be sure, the murderer in a detective novel should be given a sporting chance; but it is going too far to grant him a secret society to fall back on. No high-class, self-respecting murderer would want such odds.” -From the much-quoted 1928 essay by SS Van Dine, noted art critic and mystery writer, on the 20 rules for writing detective stories. (via Guardian)