Banff, Scotland in the 1620s. A young man walks unsteadily through the streets. Is he just drunk or is there something more sinister happening? When he collapses in front of two sisters on that dark, wet night, the women guess that he's been poisoned. His body is discovered in the house of Alexander Seaton - a fallen minister, the discovery of whose clandestine love affair has left him disgraced.

After Culloden, Iain MacGillivray was left for dead on Drumossie Moor. Wounded, his face brutally slashed, he survived only by pretending to be dead as the Redcoats patrolled the corpses of his Jacobite comrades. Six years later, with the clan chiefs routed and the Highlands subsumed into the British state, Iain lives a quiet life, working as a bookseller in Inverness. One day, after helping several of his regular customers, he notices a stranger lurking in the upper gallery of his shop, poring over his collection. But the man refuses to say what he's searching for.

Leonora Spencer has an acquaintance with death. Sixteen years ago, only she survived the brutal murder of her family. Now, as an assistant in her uncle's London morgue, she uses her photographic memory to catalogue details for his coroner reports. She also isn't opposed to helping him during postmortems if his skilled hands begin to shake. After a thief breaks into the morgue and steals a locket from a young woman's corpse, Leo is determined to understand why, even if it means going against Detective Inspector Jasper Reid's express orders to keep her nose out of it.

London, 1654. Oliver Cromwell is at the height of his power and has declared himself Lord Protector. Yet he has many enemies at home and abroad. London is a complex web of spies and merchants, priests and soldiers, exiles and assassins. One of the web's most fearsome spiders is Damian Seeker, agent of the Lord Protector. No one knows where Seeker comes from, who his family is, or even his real name. All that is known of him for certain is that he is utterly loyal to Cromwell and that nothing can be long hidden from him.

Hugh of Singleton, fourth son of a minor knight, has been educated as a clerk, usually a prelude to taking holy orders. However, feeling no certain calling despite a lively faith, he turns to the profession of surgeon, training in Paris and then hanging out his sign in Oxford. A local lord asks him to track the killer of a young woman whose bones have been found in the castle cesspit. She is identified as the impetuous missing daughter of a local blacksmith, and her young man, whom she had provoked very publicly, is in due course arrested and sentenced at the Oxford assizes.