Before the classic detection bug bit me hard, I would have considered myself of a fan of latter-era Golden Age SF above anything else — put me in the triangle formed by Isaac Asimov, Arthur C. Clarke, and Philip K Dick and I’m very happy indeed. And sometimes these dual fascinations collide, as in Asimov’s The Caves of Steel (1953) or, under the microscope today, The Patchwork Girl (1980) by Larry Niven.

In the year 2126 (we’re told it’s “one hundred and fifty-seven years after the first landing on the Earth’s Moon”), Gil Hamilton — an agent in the United Nations Police, which is “still called the Amalgamated Regional Militia, the A.R.M” — is chosen as one of the U.N.’s representatives at a conference to review elements of Lunar laws. Among those laws under discussion are “the organ bank problem”: the storing of convicted felons in stasis for six months after their conviction, after which time their bodies may be divided up for their functional parts and sent out for transplant. Hamilton himself has benefited from this, having lost an arm and received a transplant to replace it…in the process of which he also gained psychic powers and is able to control an “imaginary arm” of his own: giving him the ability to reach out to within an arm’s length and feel through any obstacle that may be there. On their first night in Hovestraydt City, one of the other conference delegates is shot with a laser through the window of his room and, since only Naomi Horne is out on the lunar surface at the time, the crime appears cut and dried.

The it turns out Naomi didn’t have a laser on her, and nowhere to hide one. Nor, in fact, was any laser checked out of the city’s secure room where they are usually kept. Equally, no short-range vehicles — which might have allowed someone else to get away and leave Naomi to take the rap — were checked out or missing, and there’s no evidence of any rocket or other vehicle having either been near, or taken off from or near, where the shooting occurred.

The case was loaded with traditional elements. Locked room, inverted, with the failed murderer locked out on the Moon. Cryptic dying message….What next? Disappearing daggers of memory plastic; broken clocks giving spurious alibis—

In many regards, this is your classic novel of detection — there’s a cryptic dying message, an investigator who says things like “I get edgy when I’ve solved two-thirds of a puzzle. That’s the time when you can get killed”, and the semi-closed circle of suspects (it has to be someone on the Moon, and we’re not introduced to them all, but it does also turn out that the culprit is someone we’ve come to know a bit) — just overlaid with the latter-era SF trappings which had probably become a little rusty by this point. For one thing, the human race has spread out into the solar system, and the “flatlanders” of Earth, the “lunies” of the Moon, and the “belters” who inhabit the outer edges of the system all have different priorities and customs. For another, everyone has different sexual mores and cultural expectations, with polygamy normalised and “birthrights” imposed to limit the growth of the species…though mostly this seems to be invoked so that Hamilton can make sweet, sweet love to hot alien babes, and then discuss whether or not he wants to have kids with any of them.

The sexual politics are interesting, but this is also the 1980s and so they also have to be a little messed up:

The desk sergeant was a lunie woman with rounded oriental features and big boobs.

Forgive me! Later I got to know Laura Drury fairly well; but I was seeing her for the first time, and I admit I stared. On her spare, attenuated frame her attractive, ample breasts became her dominant feature. You don’t picture a Tolkien elf that way.

Still, Niven does a good job in 138 pages of telling a story that (broadly…) makes sense and introduces a setting that is at once familiar and foreign. The SF trappings which may dissuade the detection fan are actually pretty neatly folded in, too, like Gil’s imaginary arm being used to explore the large area of the lunar surface quickly after the crime has occurred before anything can be hidden or projected off into the depths of space, or the observations of how water behaves under the Moon’s lesser pull of gravity giving rise to complications in the crime which result in it being solved down the line. Additionally, Hamilton is an observant investigator who recognises the importance of things like the sun on a mountain peak, or the implications of Naomi’s silence around her guilt or otherwise, to put together a sequence of events that would explain what actually happened and, thusly, who is really responsible.

What’s slightly frustrating is seeing Niven use these filigree’d touches to enable his case to be loaded with those traditional elements only to then retrocede them in a way that is undeniably rigorous but makes establishing any alternative pointless:

Psychic powers have always been undependable, haven’t they? Science was reluctant even to recognize their existence, and the law was slow in allowing psychics to testify. Tell me, Mr. Hamilton: if your unusual talent missed finding a…laser, could you not have overlooked a man?”

“It’s possible, certainly.”

Oh…so there could have been someone else out there? Or Naomi could have just hidden a laser and it not be found? It’s a good job this is a short book, because that lack of certainty over what’s been established would get frustrating otherwise. For all his talk of locked room murders — the phrase occurs at least twice — it feels like Niven’s focus here is actually more on the ripples this case will send through the universe in which it takes place: the condemnation of quickie trials, for instance, or the action which gives the story its name (though, honesty, I’d have cared more if that had happened to a more likeable character…). There’s also all the internal politicking, and the social expectations, and the clandestine nature of the sexual relations between different facets. Honestly, you could get to the end and not be entirely sure what you just read.

There’s some detection, but most of it reduces to “Gil the Arm” making an inspired guess or two (or three — I still don’t understand that dying message…). The notion of the intended victim having seen his assassin just before being shot is a good one, but I also wonder if he wouldn’t also see…something else. Equally, the motive works in the universe, but it relies a lot on what is shown in photographs that we, naturally, do not get to see, and some deductions about height that really prove nothing (lunies, see, grow taller under the less oppressive gravity of the Moon — an old idea in SF, and a fascinating one where the organs for transplant are concerned here since many of the convicted felons aren’t the right size of shape to transplant into lunies). Still, you can’t fault Niven’s ambition, and a huge amount of thought has gone into his world-building extends all the way up to a technology imagined 40 years ago that carries a surprising amount of credibility into the current age.

Those hoping for full rigour need not apply, but for the curious who want to see how logical inference and intelligent speculation may be applied in the esoteric fields of SF there is a lot here to enjoy.