This is the finest novel Helen Dunmore has written. Its unencumbered lightness does not come out of nowhere: it has been years – and books – in the making. Her first novel, Zennor in Darkness, was a remarkable debut, but in comparison suffers from a surplus of detail. Now, Dunmore knows how to let a narrative move like an arrow in flight. There is an atmosphere of Hardyesque unease as a man rows from Bristol to a glade where he has left his dead wife overnight. He must bury her fast, where no one will find her. From the start, Birdcage Walk has the command of a thriller as we keep company with John Diner Tredevant, an 18th-century property developer building a magnificent terrace in Clifton, high above the Avon Gorge. Lizzie, his second wife, does not know the details of what happened to his first. Nor do we know as much as we might suppose.

It is 1792. The French Revolution is about to have a catastrophic effect on Diner’s property speculations and this is particularly alarming given his disposition. Dunmore’s portrait of Diner is brilliant. She grasps the psyche of an oppressive, jealous, potentially violent man. Whenever Diner is cheerful, Lizzie is relieved. When he is not, she knows how to humour him and steer the subject away from peril. She knows which secrets she needs to keep from him.

Aspects of the plot recall Dunmore’s The Siege (2001). In both novels, a mother dies in childbirth, leaving a grownup daughter to raise a baby. It is interesting to speculate about why this fires Dunmore’s imagination. There is no mistaking her powerful sense of the maternal but the fascination perhaps resides in the idea of mother and child as one (the mother lives on in the life of the baby that killed her).

Bristol cannot compete with besieged Leningrad when it comes to privation but Lizzie still suffers as Diner’s money fails to materialise and he becomes more combustible. Readers are kept on edge and expect disaster. When Diner invites Lizzie down to the cellar beneath their house, it is snowing outside (Dunmore’s affinity with winter is well known) and we are filled, as Lizzie herself is, with reasonable foreboding. Whether this is justified is not the point: men like Diner set the imagination racing fearfully.

Wherever there is detail, it counts. There is a memorable scene at a dressmaker’s where a garment not collected by the first wife is inspected by the second: “I’ll never understand why she didn’t come to fetch her dress,” Lizzie muses. The dress is described as a “silvery waterfall of Spitalfields silk” and the flow of the novel resembles this silken cascade.

The novel’s cast is marvellous and vivid. Lizzie’s mother, Julia Fawkes, is a renowned late-18th century radical, a writer – her wisdom subtly described. Her stepfather, Augustus, is an academic in possession of a blind intelligence (I fancy I know his modern equivalent). He is a mixture of brilliance, kindliness and folly. He launches into “a philosophy of tea drinking according to Augustus” while missing important family happenings under his nose. “He worked on, buzzing like a fly at a window through which he would never be able to escape.” And there is the romantic poet, Will Forrest, who is wonderfully drawn, although he seems to have strolled into the story by accident. Perhaps his presence is a reminder of what falling in love is – that sense that a person has stepped out of a dream.

Dunmore, elsewhere, roots the novel in research. She never withdraws into the safety of historical distance; her writing is hazardously human. When she imagines people killed by the guillotine in France, she does not retreat from the horror of what happened, she seeks to see it as it was. As to Birdcage Walk (a path that actually exists in Bristol, leading through the graveyard of a Clifton church), this is where the fictional Julia lies buried with the inscription “Her words remain our inheritance.” Only they don’t – and it is this impermanence that is another of Dunmore’s poignant themes in a novel that deserves to be cherished and to last.

• Birdcage Walk by Helen Dunmore is published by Hutchinson (£18.99). To order a copy for £14.24 go to bookshop.theguardian.com or call 0330 333 6846. Free UK p&p over £10, online orders only. Phone orders min p&p of £1.99