A science fiction novel by Isaac Asimov, first published in 1954 by Doubleday. It was Asimov's ninth novel, and the first in what has come to be known as the "Robot series".

As the Good Doctor tells it in his self-titled autobiography, the origins of The Caves of Steel begin in a conversation with Horace Gold, then editor of the (now long-defunct) magazine Galaxy Science Fiction. Gold was trying to convince Asimov to write a novel involving robots taking human jobs in a future world crippled with overpopulation. Asimov balked at the idea as too depressing, but Gold insisted, suggesting that he write it as a mystery novel. This struck a chord with Asimov, perhaps especially since he was at the time growing more and more distant from his mentor, John W. Campbell, Jr., who had frequently said that it was impossible to have a SF mystery, because the detective could always pull out some gadget that would magically solve the case. Asimov sought to disprove Campbell's pronouncement in The Caves of Steel.

Background

The Caves of Steel takes place sometime several thousand years in the future. The Earth's population has expanded to a burgeoning eight billion, which has resulted in a number of radical changes. The most striking of these is that everyone now lives underground, in huge Cities going a mile deep and spanning hundreds of miles across. (The actual size of these Cities is perhaps best illustrated by the offhand mention of Jersey City and White Plains as "boroughs" of New York City.) Special privileges - like having a sink in one's own apartment, or getting a few meals of real food a week instead of flavored yeast - are allotted in accordance to one's rated importance (though noone is left to starve). One major consequence of this way of life is that nearly all Earthmen are agoraphobic, unable to stand the open spaces of the surface - the very food and resources which keep their civilization from collapsing are grown and mined by robots. Most Earthmen would rather not think of that, however; most hate robots passionately, partially out of fear that they will steal valuable jobs from human beings. Certainly, they could not fear the robots themselves, for all robots have hardwired into their positronic brains the Three Laws of Robotics:

1) A robot may not injure a human being, or, through inaction, allow a human being to come to harm.
2) A robot must obey the orders given it by human beings except where such orders would conflict with the First Law.
3) A robot must protect its own existence as long as such protection does not conflict with the First or Second Law.

Through the invention of a "hyperspace" engine that allows ships to travel hundreds of lightyears in mere moments, mankind has settled on 50 more planets throughout the galaxy; but no Earthmen have emigrated to these worlds almost since the initial wave of colonization, some three thousand or so years earlier. These "Spacers" have, through the use of robots for manual labor, the lack of indigenous disease, and the general advance of medical science been able to extend their lifetimes to be several centuries long. They keep their planets relatively empty - the most populous world, Aurora, has no more than 200 million inhabitants at any time. They hold Earth in the highest contempt and bar the immigration of Earthpeople, who they consider to be at best genetically inferior (and at worst, subhuman). Even if most Spacers did not consider them to be little more than barbarians, it would be dangerous for one to remain in close proximity to an Earthman for long - having being born and raised on worlds where there is no viral or bacterial disease, their bodies have severely weakened immune systems, to the point where even the common cold could potentially be lethal.

There are some Spacers, however, who feel that it is ultimately in the interest of humankind for Earth to be modernized - in particular, for it to develop the same "robot culture" present on the Outer Worlds. On Earth, robots are only used for farming and mining on the surface and for a few limited tasks in the Cities - but on Aurora and its sister planets, robots perform nearly all forms of manual and skilled labor. All humans on Spacer worlds are free to pursue more intellectual professions, and each person has a small army of robots at their beck and call. Spacers consider this to be the most civilized way of life imaginable, and for the purpose of helping to bring it to Earth, the Spacers have set up a small domed city on the surface above New York, nicknamed "Spacetown". Earth, for its part, resents the Spacers deeply and is suspicious of the "help" Spacetown is supposed to give, but has no choice but to appease the vastly powerful Outer Worlds.

The Novel Itself

It begins shortly after the murder of a resident of Spacetown - the prominent roboticist Roj Nemennuh Sarton, killed by a blaster fired at the chest. The Spacers insist that the culprit must be an Earthman - no blaster has been found in or around Spacetown, and no Spacer had left the settlement. Yet the same scanners that detected no Spacer leaving the town with a blaster would also keep an Earthman from being able to enter with one. There were plenty of ways into Spacetown by the surface, of course - yet what Earthman, no matter how fanatical in his hatred of Spacers, could brave the unenclosed fields surrounding the town?

Given the task of solving this seemingly impossible mystery is Plainclothesman Elijah Baley, rating C-5, a detective in the New York Police Department. Warned that failure to find the murderer may result in declassification (that is, losing one's job and status and being reduced to minimal living requirements), Baley sets out on his mission - but with one more caveat. The Spacers, it seems, do not entirely trust a lowly Earthman to solve this case himself. Thus, they require that he be partnered with one Daneel Olivaw. Daneel is a humaniform robot - not only does he look human, but his brain was designed to be as human as possible (with the exception that he is still bound by the Three Laws) - and he was built in part by Dr. Sarton himself. Programmed with what he calls a "desire to promote justice", he and Baley set out to uncover the conspiracy behind his creator's death.

The Caves of Steel is one of those science fiction novels that truly stands the test of time. There are a few references that make it seem dated - in particular, Asimov's estimate of eight billion Earthmen seems way below the mark - but they are relatively insignificant. The story is fast-paced and engaging, and the revelation of the murderer's identity represents one of the few times a novel has actually surprised me. Each time Baley thinks he's found his lead, it turns out being a dead end, but he presses on and shocks everyone with his success. The Caves of Steel is Asimov at his best, giving us a hard SF mystery with no cheap gimmicks - and perhaps most importantly, no magic gadgets.
The Three Laws, as quoted, are under copyright by the Asimov estate. Fair use and all that.