Harris places her trusted hero, American doctor Thomas Silkstone, back in 1783 England, where the rift between the English and the Colonials is still clearly defined after the War of Independence. The aftermath of the conflict, however, pales in comparison to the acrid Great Fogg that suddenly descends in the Lincolnshire landscape and claims the lives of numerous people with respiratory ailments, especially the young and old in the poor neighborhoods and farms.
While for the moment Thomas’s beloved, Lady Lydia Farrell, remains safely ensconced in Boughton Hall, Oxfordshire, the fog itself (“a bank of billowing cloud, its great curves and sweeps and pillows of vapor easily visible, like the full sails of a galleon”) is a curse for the rest of the population. As the fog makes ordinary men doubt their own judgment, the local priest, the Reverend Lightfoot, comforts the bereaved and buries the dead. From the outset, Lightfoot seems to take a sadistic pleasure in putting dread into the hearts of simple God-fearing folk.
In a faithful attempt to recreate the real-life circumstances of the fog, Harris ricochets Thomas, Lydia, and their friends and enemies back and forth in a whirlwind from bucolic Boughton Hall to the wretched, stinking streets of London. Even before the first deaths occur, Dr. Thomas detects a certain strangeness in the air, a strangeness that is manifested in Lady Lydia’s long-lost son, who was born six years previously with a horribly crippled arm. While Harris depicts Lady Lydia as swept away by circumstance, Lydia’s own regrets at giving away her boy lead Thomas onto his promised mission: to track down her child.
From the first page, the action is a bone-jarring buildup of near-death experiences as Thomas uses his repertoire of considerable anatomical skills to get to the origin of the noxious fog while the steaming stew of London simmers in an intolerable heat. There’s a constant sense of unease in the novel, “a place where nature speaks its own language.” When Amos Kidd, Boughton’s loyal gardener, gets caught in the thickening haze, his wife--“evil temptress” Suzannah Kidd--turns in solace to Joshua Pike, the local knife-grinder. When Suzannah and Pike are inadvertently blamed for a series of deaths, events take a sudden turn for the worse, and Thomas finds himself plunged into a murder investigation.
From one climactic scene to another, the anxious villagers must battle Pike, whose efforts to call the men into action for higher wages comes to nothing. The fog’s influence turns out to be much more lingering and malevolent than at first thought: a malignant fear has taken hold. In an effort to stop the nagging coughs, Thomas works with Oxford’s apothecary to make up batches of formula to distribute among the many sick who see the event as a trial sent from Above. Still, a vicious murderer or murderers remain on the loose, seemingly killing at random. Lydia’s neighbor Lady Thorndike disappears, while Lydia’s old enemy Sir Montague decides he wants Lydia’s son for himself to be used as bargaining tool in the form of a “feral child” who will perhaps finally secure the future of Boughton Hall.
The story is bracing and intense but weakens a bit in the later chapters as Henry’s continued love for Lydia is put to the ultimate test and Lydia’s desire to find her son becomes evermore exhaustive. Harris weaves actual historical incidents and personages into the story and gives the reader various views of London and Oxfordshire, from the gritty to the gracious. The author once again does a fine job of depicting an England of another time and of a much harsher sensibility.