Mark Sabre is a man forever at odds with everyone else, as while they are quite comfortable in the inherit correctness of their opinions, he can’t help but play the devil’s advocate and consider where all his opponents are coming from. It’s a trait particularly irritating to his wife, Mabel. He’s full of ideas and ideals, but she had no interest in them, and she’s frustrated by his lack of class consciousness and propriety, being especially insulted by his “sticking up” for their social inferiors.
Then there’s Lady Nona Tybar. She was once in love with Sabre, and now that she’s married to Lord Tybar, she realizes that she loves him still. Tybar is an unrepentant rake who revels in his adultery and makes no secret of it to Nona. Nona gets Sabre and she appreciates him — she’s possibly the only one who does.
And there’s Twyning, who works with Sabre. Twyning is a conniving, vindictive man who rather hates Sabre, because he assumes that everyone else is as conniving and vindictive as himself. Twyning is ever-eager to force Sabre out of the office to consolidate his power and to promote the career of his beloved son, Harold.
And finally, there’s the war — WWI. The story begins a few years a before, builds as tensions mount, reaches an uncomfortable plateau while the fighting lasts, and unravels as the war draws to a close. Sabre, never mind his poor health, enlists. A companion is employed for his wife while he’s away — Effie, the daughter of one of Sabre’s coworkers. Effie starts out as a vivacious girl, but Mabel’s bullying grinds her down. She remains on good terms with Sabre when he returns on leave. He treats her as a sister. Mabel isn’t jealous, per se, but the relation offends her sense of propriety. She fires Effie without warning just as Sabre returns to the front.
Nine months later, Sabre is wounded and discharged home. His wife receives a letter from Effie that positively thrills her with vindication: Effie gave birth to a baby, she refuses to give it up or say who the father is, and she’s consequently been turned out. She begs that the Sabres take her back. To Mabel’s astonishment, Sabre insists that they do.
Effie moves in and Mabel moves out. Sabre takes the full brunt of society’s disapproval. His friends refuse to receive him, he’s all but fired from his job, and his wife files for divorce. And all along, it never occurs to him that it’s because they think he’s the child’s father. It’s so far from his mind, it’s inconceivable. Effie realizes what pain she’s brought on him, and so while he’s away for a few days, she’s kills herself and the baby. Sabre is accused of their murder.
At the trial, Twyning is on the prosecution’s side. It’s the great opportunity he’s been waiting for — to get rid of Sabre, permanently. And he very nearly does, until Nona appears. The Tybars are very influential in local affairs, and however unconventional her assistance — busting into court during Twyning’s testimony and loudly proclaiming him to be an “experienced and calculating liar” — it’s enough to sway the jury.
Directly after, alone at home, Sabre finds a suicide note that Effie had hidden where she knew only he’d find it. It begs his forgiveness and names the child’s father as Twyning’s son, Harold. Sabre, in a delirious state, takes his service pistol and rushes to the office — intent on killing Twyning. He finds him at his desk, very altered and at the point of tears, having just received word that Harold was killed in the war. Sabre consoles him and decides to destroy the note.
In declining health, Sabre suffers a brain hemorrhage that leaves him paralyzed and near death. When he recovers, several months later, he finds Nona with him. Tybar, too, had been killed in the war — unrepentant till the end. Although he tries to force her away so that she might not share in his disgrace, she refuses to leave. The story ends some time later with them newly married.