Sadie Jones's highly entertaining third novel seems perfectly conceived to appeal to two current popular tastes  our fascination with the Edwardian country house and the revival of the English ghost story. The Uninvited Guests marks a stylistic departure for Jones too  on the surface the tone is lighter and more comic than her two previous novels, The Outcast and Small Wars, which both examined the unravelling of family relationships and the ways violence and tragedy can erupt from repression. But surfaces can be deceptive, as Jones's characters discover over the course of one satisfyingly stormy night. The conventions of middle-class English manners are revealed as too flimsy an overlay to hide the filthy passions and cruelties that seethe underneath.

Sterne is an isolated 18th-century manor in the north-west of England, bought by Horace Torrington and now home to his widow Charlotte and family. Elder children Emerald and Clovis resent their mother's new husband, Edward Swift, who departs for Manchester one morning in April 1912 in the hope of securing a loan to save Sterne, which is crumbling for lack of funds and may have to be sold. As storm clouds, literal and metaphorical, gather over the house, preparations begin above and below stairs for a dinner in honour of Emerald's 20th birthday.

Thus far, it's an elegant comedy of manners with the usual undercurrents of jealousy, desire and conflicting loyalties. But the mood changes when Clovis, returning from the station with family friends, brings news of a dreadful accident on a branch line. A mysterious representative of the Railway requests that the survivors be put up at Sterne.

These uninvited guests appear as if from nowhere as dusk falls, heralded by a chilling gust of wind; they seem to multiply as the night goes on, and give off a growing scent of decay  though none of this alerts the family, who have not read the novel's epigraph from Byron's Don Juan: "Their table was a board to tempt even ghosts/ To pass the Styx for more substantial feasts."

The ghost story genre is necessarily formulaic, which is perhaps why it continues to fascinate writers; the challenge is to create something new from within its confines. Jones concentrates on the way the unexpected intrusion affects the family and their friends, bringing out their best and worst qualities, revealing long-buried secrets and unexpected depths of passion and rage. Where there should be kindness for the traumatised passengers, there is at first resentment and impatience at the disruption, made all the sharper by the fact that the incomers are from third-class  all except the dashing, wolfish Charlie Traversham-Beechers, a sinister figure from Charlotte's past.

Jones has a vivid eye for period detail, lingering lovingly on shimmering dresses, hairstyles and jewellery, so that the contrast is all the more vivid as filth, mud and dissolution gradually strip away the glitter and finery that separates the classes, reducing all the characters to a common, almost bestial, humanity. "You were [kind], in the end,"' murmur the passengers, when all the lessons have been learned.

The Uninvited Guests also carries echoes of Shakespearean comedy; though menace hovers close to the main characters, it never tips into genuine danger, and there is a pleasing resolution in which everyone assumes their proper place, a little wiser and less proud. Jones shows that she can turn her talent for storytelling to a more stylised form with a light and playful touch, and without compromising her sharp insights into the human heart.

Naming, as the book of Genesis affirms, is a dominant and defining act. For parent or for author, the choice of a name creates echoes and reveals a ragged tapestry of relationships. The more unusual the name, the stronger the associations. In The Uninvited Guests, Sadie Jones calls her young male lead character Clovis, and thereby summons up Saki's tart, macabre voice and his stories of Edwardian country-house life with its shibboleths, comeuppances and cruelties. Saki (HH Munro) was greatly interested in revenge, with the supernatural frequently acting as its agent. His recurring hero, Clovis Sangrail, is a lord of malice and misrule, cloaked in the lazy elegance of a young English gentleman.

Sterne, the Edwardian country house which is the setting for The Uninvited Guests, is under threat. Clovis, Emerald and Smudge Torrington, their mother Charlotte and her second husband, Edward Swift, are all clinging on to Sterne, but there is no more money. The house will have to be sold, unless Edward can pull off the vaguely shameful feat of borrowing from "an industrialist of low morals". But meanwhile there is Emerald's 20th birthday party to be held, in Edward's absence. The neglected youngest child, Smudge, plots a Great Undertaking in her bedroom. Charlotte hides a guilty past, while her children don't bother to conceal their resentment of the man who has replaced their father. So far, so Saki. But Saki was of his time and he died with it, an over-age volunteer who enlisted as a private and was shot by a sniper in a shell-crater on the western front. Jones, by contrast, looks back on the Edwardian era across 90 years of interpretation and cultural accretion.

The ingredients have been used so many times: the isolated house that generates its own society, the sharp class distinctions, the hurdle race towards matrimony, the aromas of crime, mystery and intrigue. Sterne's giant black yews, ancient, extravagant roses and softly bowed boards are familiar to the modern reader, not because they reflect our first-hand experience but because books, films and television have made them, oddly, our own. Jones plays with this familiarity, prompting it, teasing it, and then, disarmingly, undermining it. Her tone is coolly playful, even detached.

The birthday party is to be a small affair, just family and a few close friends. It expands, terrifyingly, when a railway crash brings to the house a flock of stunned survivors, like birds who have flown into glass. The railway authority decrees that it is Sterne's responsibiity to take in these travellers until further arrangements can be made. They are third-class passengers, and immediately recognised as such by Sterne's inhabitants, who lurch from pity for the "poor things" to wariness in case they become "rowdy and unmanageable now that they're warming up and realising their good fortune". Their good fortune, as Jones slyly emphasises, consists in being given a cup of tea and kept pent up, away from the other guests. Even the relatively considerate Emerald "did not stop to consider that the morning room was not large, or that the fire in it may be dying". The passengers, hungry, quelled but desirous, seem to grow in numbers and uncanniness as the evening wears on. Meanwhile, Jones's own lord of misrule, Charlie Traversham-Beechers, takes charge of the party.

Where Saki would be ruthless, Jones relents. There is sunlight and the smell of bacon. There is resolution, even restoration. Evil only seems to show its face, and it is energy itself which becomes the hero of the narrative. The task of the living, it appears, is to make sure that the dead stay dead, rather than to appease them. Fear won't do it; anger won't do it, and it turns out that the operative force has got to be love. The story scuds along, veering close to pastiche, although the luscious prose is precisely steered.

But another current is at work within the novel, and because The Uninvited Guests is a creation of the 21st century, historical knowledge cannot help but force itself on the narrative. Clovis, the guests Ernest and John and all the other young men may sit at their breakfast tables on a spring morning eating bacon, relieved that the battles of the night are done. Jones and her readers know that they are plunging towards a collective fate. Mud and death wait for them; the passengers are not the only ghosts in the novel. And we, reading it, see for a moment our own ghostliness coming through to us.

Helen Dunmore's The Greatcoat is published by Hammer.