London, 1936: a young woman stands in the dock at the Old Bailey accused of poisoning her husband with arsenic — Lady Beatrice Langston, clever, composed, and inconvenient, married Sir Hugh Langston three months ago and now the books on toxicology were in her library, the quarrels were overheard, the servants have testified, and the prosecution's case is neat, complete, and very convenient; as the Belgian Detective and his loyal companion move through a Belgravia house thick with pride, silence, and the slow decay of an old family name, they follow a hidden compartment behind a dining-room panel, a butler whose loyalty hardened into something lethal, a family lawyer whose debts outpaced his charm, a mother-in-law who chose the house over the truth, and a dying man's letter hidden where only a frightened husband would think to look; The Newlywed's Shadow is an original Golden Age–style mystery about poison, prejudice, and the discovery that the most dangerous thing a woman can do in a great house is refuse to be small.