Joe Lampton, demobilised at the end of the Second World War, is starting in a new job with the Municipal Treasury in the town of Warley. He had been a POW who spent his captivity studying to pass his accountancy examinations. He is an orphan whose parents were killed in an air raid against his home town. He is determined to make something of himself, targeting a high-paid job with a thousand a year salary. He notices, shortly after arriving, a young man with an expensive car and a pretty girl friend and he realises that this lifestyle and appearance is what he aspires to. The book centres on Joe's efforts to secure a future he can take pride in. In Warley, he takes lodgings with the Thompsons, a middle class couple living in the better part of town, known locally as "T'top". Lampton is delighted to find himself already socially advantaged by taking, quite literally, a "Room at the top", and this serves as a metaphor for his ambition to better himself and to leave behind any vestige of his former life and acquaintances, many of whom he characterises as "zombies", lacking any trace of genuine life and character. Everything about Warley is an improvement on his former life in Dufton. The Thompsons introduce him to the localamateur dramatic society, which is in need of new faces, and there he meets Susan Brown, the only daughter of a very successful local businessman. He also meets the apparently cold and standoffish Alice Aisgill, who plays many of the leading lady parts. Alice and Joe are drawn together through intelligent conversation, and their relationship soon becomes a highly rewarding sexual one, in spite of what Alice perceives to be a significant age difference. Although supposedly betrothed to Jack Wales, the dashing scion of a wealthy local family, the naive and childish Susan allows Joe to woo her; meanwhile, Joe and Alice develop their relationship through clandestine sex in a borrowed apartment. Joe has a way with words, and convinces Alice of his affections for her – consolidating this during a stolen few days away in a country cottage, during which Alice declares her undying commitment to Lampton; in the meantime, Joe's silver tongue and persistence also enable him to seduce Susan, who becomes pregnant. This is part of Joe's plan; Joe loves Alice, but wants to marry Susan so as to achieve his social ambitions, and to demonstrate that he can outdo Wales in his battle for the girl's affections; people are becoming aware of the relationship with Alice, and exposure threatens his future, so Joe is not averse when Susan's father insists on their immediate marriage, sweetening the offer with a "thousand a year " job, on condition that he drop Alice for good. Alice, distraught at the break-up, is found severely injured after a drunken car crash near where she and Joe first consummated their love, and dies shortly afterwards. Room at the Top concludes with Joe drunkenly attempting to cope with remorse over Alice’s death and his successful scheme to marry upwards. He is reassured that nobody blames him for Alice's death – but he knows this is wrong, and the book closes with him aware of his conscience, forced to live with his guilt and his responsibility for what has happened.
