The Talented Mr Ripley by Patricia Highsmith.
A bit of a rum cove, Tom Ripley. Fingers in pies, a few little shady ventures on the go, most recently a bit of low-level financial confidence trickery, but nothing serious. I mean, it's not like he's murdered anybody.
When Herbert Greenleaf hails him across a New York bar, then, Ripley's first reaction is to guiltily assume one of his schemes has been rumbled, but in fact Greenleaf has recognised him as an acquaintance of his son, Dickie. Overestimating the closeness of their friendship (something Ripley actively encourages him in), Mr Greenleaf offers Ripley a job - go to Italy, where Dickie has been swanning about for some time at his father's expense, and persuade him to return home, join the family business and generally knuckle down to adulthood and responsibility.
Since Mr Greenleaf is covering all his expenses, Ripley readily agrees and sets off for Italy. Once there he contrives a supposedly chance meeting with Dickie, who is sunning himself on the beach with his American friend Marge Sherwood. A bit of stalking activity later and Ripley is being invited to move from his hotel into Dickie's rented house. His burgeoning friendship with Dickie and his virtual monopolising of his company leave Marge feeling excluded and resentful, and when Ripley starts aping Dickie's clothing and mannerisms she becomes suspicious of the nature of their relationship. Dickie starts to have similar qualms himself after he comes back to the house to find Ripley wearing his clothes, and there is a cooling-off of their friendship. Seeing his free ride on the Greenleafs' money coming to an end, Ripley persuades Dickie to come on a farewell trip to San Remo, during the course of which they go out in a dinghy and, seeing that they are out of sight of land and other boats, Ripley impulsively murders Dickie by caving his head in with one of the oars and then weighs his body down with the anchor and dumps it over the side. He then takes the boat to a secluded spot near the shore and scuttles it.
So now what? Well, Ripley has a few tricks up his sleeve, like some impersonation and signature-forging skills, so he decides that he's going to become Dickie Greenleaf for a while. He gathers up Dickie's clothes and passport from the house and heads off to Rome, where he puts his forging skills to good use by writing some letters: to Dickie's parents assuring them that he's still alive and that they should continue sending him the allowance cheques, and to Marge suggesting that perhaps they shouldn't see each other for a while.
Obviously the subterfuge of Ripley being Dickie is only going to hold for as long as he can avoid meeting anybody who knew Dickie while he was still Dickie, i.e. alive. So when Dickie's old friend Freddie Miles calls round, Ripley has to do some frantic reversion into being Tom Ripley for a while; trouble is, the housekeeper knows him as Dickie Greenleaf, and so eventually, after some sitcom-style misunderstandings, Freddie smells a rat and comes back to confront Ripley about it, at which point Ripley has little choice but to murder him with an ashtray, bundle his lifeless body into his car and dump it among the tombs lining the Appian Way.
Things are starting to get complicated: the police are sniffing round after finding Freddie Miles' body, and they're also concerned that this Tom Ripley bloke seems to be missing, and both men knew Dickie Greenleaf and saw him not long before they disappeared. So Ripley (as Dickie) decides to lie low in Sicily for a bit until the heat's off. Eventually he has a better idea - return to Italy, revert to being Tom Ripley again, and pretend to have been off touring round Italy and be unaware of all the fuss. So he contrives to turn up in Venice and report to the police to confirm that he's not actually missing after all.
So the question now becomes: what's happened to Dickie? In due course Dickie's father (with a private detective in tow) and Marge turn up in Venice to ask Ripley the same question, and Ripley steers them towards concluding that he must have killed himself, possibly out of remorse after murdering poor old Freddie Miles, or possibly not. All seems lost when Marge finds Dickie's rings in a trinket box at Ripley's rented house, but (after briefly toying with the idea of murdering her) Ripley manages to persuade her that Dickie gave them to him for safekeeping shortly before vanishing, almost as if he was not coming back, eh Marge? Fortunately Marge seems convinced.
So Ripley seems finally to be clear of worry. The only remaining fly in the ointment is that now he's not Dickie any more the regular income has dried up. In fact pretty much everyone seems to have concluded that Dickie is dead. So with one last facsimile of Dickie's signature Ripley produces a fake will on Dickie's old typewriter (which he then disposes of in a canal) leaving everything to Ripley. Problem solved!
Having your major protagonist be an amoral murderer would have been revolutionary enough in 1955, letting him get away with it and leaving him with a nice house in Venice and access to his victim's trust fund even more so. It's interesting that both film adaptations of the book, Plein Soleil aka Purple Noon in 1960 and Anthony Minghella's The Talented Mr Ripley in 1999, changed the ending to give Ripley a bit of comeuppance. In the earlier film Dickie's body slurps up from the deep at an inopportune moment, and in the Minghella film Ripley is portrayed as having embarked on a homosexual relationship with an Englishman, Peter Smith-Kingsley (who appears briefly in a much more minor role in the book), whom circumstances then dictate that he has to kill to avoid being rumbled, at, presumably, some psychological cost to himself as well as the risk of being discovered as the killer.
It seems a shame that they had to make the gay subtext explicit in the later film, because, well, it stops being subtext, then, doesn't it? The thread running pretty clearly through the book is that Ripley (in addition to various psychological issues, like, you know, murdering people) is probably at least partly a repressed homosexual (possibly like the narrator of Demian). That seems pretty clear from his tortured relationship with Dickie, and also his attitudes towards Marge: resentment of her relationship with Dickie at first, and a more general dislike later. It's interesting that the casting of Gwyneth Paltrow as Marge in the Minghella film makes her a great deal more attractive than she's portrayed as being in the book, but of course in the book we're seeing her through the distorting lens of Ripley's sexual disgust. The other thread that runs through the book is the passing of the old class divisions - Dickie and Freddie Miles' attitudes to Ripley are slightly disdainful, as he doesn't have their urbane upper-class manners and easy social skills, or the right old school tie, but he comes out on top in the end as he's not only cleverer than they are, but not as effete and sybaritic and lazy. That's your actual meritocracy in action, right there. And murder, also.
Convincing portrayals of proper psychopaths in fiction are quite rare; there's Hannibal Lecter, but he's a cartoon character compared to Ripley, who displays all the standard symptoms - poor impulse control, little or no empathy, a plausible veneer of normality, no guilt or remorse for his actions - but without the pantomime silliness. I suppose there's an echo of Lolita here as well, in that the central character has few redeeming features and commits a whole slew of atrocities throughout the book, but we still retain a bit of sympathy for him at the end, probably more so for Ripley than for Humbert Humbert, actually.
Anyway, this is terrifically sly and clever stuff, as long as you haven't got the sort of highly developed moral sense that demands that people who do wicked things get strung up good and proper for it. In fact it's so cunning you could put a tail on it and call it a weasel.