#RetroHugos1941 The Reign of Wizardry, by Jack Williamson
I thought I was going to give up on the sf novels of 1940, but I'm glad I didn't - this is a very competent retelling of the Greek legends of Theseus, with some parts of other legends thrown in, that rises to a cracking good conclusion. I don't think it will (or necessarily even should) win a Retro Hugo but I'll certainly give it one of my nomination slots.