This little book is listed as science fiction, but is far closer to fantasy. It's Bradley's second -- not first, as is commonly said -- "novel" in print (we'll call it a novel though it doesn't make 40,000 words), and though yes, you can see the writer who would develop across future years, I'm rather surprised Door Through Space snuck past the editors at Ace. It's a major rework of a story, "Birds of Prey," which she sold to Venture (magazine) in 1957, and I wonder if the short story worked better ... if the additional world-building for Door caused some of the book's problems. Hmm.
There are some real difficulties, which the editors at Ace seem to have ignored. First and worst, the novel doesn't end, it just STOPS. The ending is truncated, as if Bradley were simply ending a chapter. To my knowledge there isn't even a sequel to Door ... it just runs face-first into a wall and stops on something like page 115. Obvious this didn't bother the gaffers at Ace in '61, so I can only assume readers were less demanding at the time. One thing is certain: if Bradley were trying to sell this one even a very short while later, the rejection letter would wing back with boomerang-like swiftness.
Then ... although the world building is extraordinary, given that she did the whole thing inside of 40,000 words (with the gift of the writer trained in the demanding short story marketplace), the same world building suffers from a least one blazing non sequiteur that I can't get out of my memory:
The indigenous population of this world, Wolf, demonstrates a kind of late iron age native tech: everyone wears furs, rides horses, swings swords, cooks over open fires, and chains their women. Sounds like twelfth century Europe. Fair enough. Running beneath this is a weird tech-like "something" drawing on a level of science beyond anything we know even in the twenty-first century: the troll-like nonhumans from the boreal north make "toys" which transcend tech. Magic? Even this is fair enough ... but at one point Bradley states that imported vacuum tubes are incredibly valuable among Wolf's people. To whom, for what? There's no electricity outside the Terran compound, and the dwarfish alchemy behind the evil "toys" so far transcends any tech *we* understand today, those indigenous dwarfs would fall down laughing at vacuum tubes. In order words, vacuum tubes are worthless ... no editor picked this up. (They also missed some grammatical gaffs, repeated words and so forth. Pulp fiction is as it is.)
Still, 95% of the world building is very impressive, and Bradley's prose is often fine. One of the head-scratchers is the chapter devoted to the torture of hero Race Cargill: not the torture itself, which was little enough to skate through without plummeting into s&m, but ... my gods, this woman, at this time, had no bloody idea what physical pain feels like, and how long injury takes to heal. Bradley was thirty-ish when she wrote Door, and didn't seem to have yet suffered enough to know what the hell she was writing about. [rolls eyes] Doubtlessly, time and experience cured this.
I also have a minor problem with the bondage of woman issue, but I acknowledge that Bradley is crafting a very alien culture, some of which is based on nonhuman values. Human morality -- much less the moral high ground we assume in this age of equal human rights -- is out of place here. But this aspect does take me two steps closer to the John Norman twaddle than I want to tread. We'll just have to overlook this and focus on Bradley's creativity and the parts of Door Through Space that zip along, Robert E. Howard fashion, like a swashbuckler.
Two stars. It was okay in its own way, particularly given the time in which it was written, but I'm honestly surprised to be underwhelmed by the work of Marion Zimmer Bradley, no matter how early in her career this fell. She was no juvenile when she wrote this. Hmm.