Roadside Picnic by Arkady and Boris Strugatsky.
Redrick "Red" Schuhart is a stalker. What that means is that he makes a living scavenging various mysterious alien artefacts from The Zone, one of half-a-dozen sites on Earth where alien visitors arrived briefly some years before, before buggering off again as quickly as they came.
These Zones are cordoned off from public access, partly for the public's own safety, since there are physical objects there that can maim or kill, as well as more nebulous things like weird local concentrations of gravity that can crush vehicles (and, needless to say, people) like a grape. The exclusion of Joe Public is also partly prompted by less altruistic motives, inevitably, as some of the alien artefacts, while potentially dangerous if mishandled, have wide-ranging applications for energy, public health, and the like and The Man wants to ensure he gets his cut.
With anything like this there's going to be a thriving black market as well, of course, as long as people are prepared to pay enough to make it worthwhile for other people to risk their lives by breaking into the Zones. Which is where Red comes in. He's an old hand at navigating round the weird death-dealing phenomena to get to the good stuff, and being able to get it out of the Zone and move it on to the right people. Red takes the occasional occupational hazards in his stride - a two-year jail sentence, his old co-stalker and mentor Buzzard Burbridge falling into a pool of alien goop and having his legs dissolved below the knee, another co-stalker snagging some alien spider-web stuff and subsequently dying, that sort of thing.
One of the problems with being a stalker, apart from the constant danger of getting arrested or shot or stumbling into a gravitational anomaly and getting turned inside-out, is the long-term effects of spending a lot of time in the Zone - there's no measurable radiation being emitted, but something happens to stalkers, and those that don't find themselves rendered incapable of having children altogether produce offspring that are a bit, well, odd. Red's daughter Monkey is a case in point, being so named because, well, she looks a bit like a monkey.
It's in a desperate attempt to generate a lump sum to get some (almost certainly futile) treatment for Monkey that Red takes on One Last Job - finding the Holy Grail of stalkerdom, the Golden Ball, which supposedly has the power to grant wishes. Only old Buzzard has seen this before, and he's passed on two vital pieces of information to Red: not only where it is, but also the importance, on this trip more than ever before, of taking a co-stalker with you - you see, one of you will have to die before the other can get to the Ball.
Needless to say Red decides not to share this piece of information with his co-stalker - in a piece of cruel irony, Buzzard's son Arthur - and once the inevitable unpleasantness has been got out of the way, Red is free to approach the ball, by this stage in a state of almost religious ecstasy.
And then what? Well, we never find out, so you'll have to make up your own mind. Judging by what's gone before, a sudden burst of cleansing joy and happiness whereby everything is OK and no-one has to suffer ever again is probably unlikely, though. I think a useful comparison is to view this book as being a sort of polar opposite of the Iain M Banks books within the science fiction genre (with my usual caveats about whether that categorisation is even sensible or useful) - the Bankses are all about the glorious possibilities of technology to make worlds better places to live, laugh, hang-glide and have weird freaky sex, with the denizens of the Culture representing a sort of perfected version of humanity, while Roadside Picnic is about some unknown aliens dropping into Earth on their way somewhere else (possibly a hang-gliding and freaky sex party, who knows) and just randomly dumping a load of garbage with no particular purpose in mind, probably not noticing the human race even existing, and with no intention of ever coming back. It's very much like, as the book's title suggests, a bunch of people having an impromptu picnic by the side of the road and leaving behind a load of orange peel, biscuit wrappers and plastic forks without any thought to the effect on the local wildlife. A profoundly gloomy view, you might say, but that sort of grinding mundane reality whereby contact is fleeting, baffling and unaccompanied by any sort of context, let alone an instruction manual, seems a much more likely way for any First Contact scenario to play out.
The other way in which this differs from the Bankses is that they are in the main quite big chunky books, while this is a slim 145 pages. There's enough ideas here to fill a much bigger book, though, if you were less inclined to terseness and leaving the reader to work things out for himself. I thought it was excellent in a grimy and gloomy and weird and haunting (and typically Russian, one might argue) sort of way.
Roadside Picnic is most famous for being the source material on which Andrei Tarkovsky's celebrated 1979 film Stalker is based (here's a 5-minute version). Pretty loosely based, by the sound of it, even though the Strugatsky brothers wrote the screenplay. I therefore consider this further confirmation of my earlier theory about short novels being easy to adapt into films. Tarkovsky's most famous film Solaris was also an adaptation of a science fiction novel, this time by Polish author Stanisław Lem. I haven't seen either of the Tarkovsky films, though I have seen the 2002 Steven Soderbergh/George Clooney version of Solaris, which I thought was pretty good in a glum sort of way. I expect the Tarkovsky version is even glummer, though.