I'm not a big MZB fan, as I find her Problematic to say the least. And I didn't care for Mists of Avalon even in the 90s. But I adore Ace Doubles! So I thought I'd see what this one was about. It's only her second novel, from 1961.
I was forcibly reminded of Leigh Brackett's Stark novels. I'm going to call this story a shameless Leigh Brackett ripoff.
This guy, Race, used to be a secret agent, but he's been working in an Earth government office for years, in a little outpost on Wolf, that isn't quite a colony. Wolf has a large population of both humans and non-humans, but they're all pretty strange. Race's sister, who married his former partner and best friend and joined his culture, shows up needing help, so Race goes off to find his former friend, kill him, and also save the planet from the nefarious conspiracy that threatens it. And probably he'll fall in love with a girl.
There's a lot of running around in various cities and haunts, and uncanny characters, and whatnot. Lots of strange cultural customs. One of the more obvious elements of Wolf's culture is that women wear decorative fetters and chains to advertise their status as protected females. Race has always disliked this feature, but by the end he's a fan. The whole thing is pretty oogy.
So, I didn't much care for it, but it was kind of fun to read in a weird way. The other side of the double novel was boring and impenetrable, so this was probably the 'good' side.