Taking a break from his holiday visiting his nephew, Jim, Athelstan Digby agrees to look after the old bookshop of Keldstone so that his hosts, the Lavenders, can attend their cousin's funeral. On the first day of his tenure, three suspicious characters enquire after a copy of 'The Life and Times of Mr Badman' by John Bunyan. When a copy mysteriously arrives in a bundle of books brought in by a young scamp, and is subsequently stolen, Digby moves to investigate the significance of the book with his nephew, and the two are soon embroiled in a case in which the stakes have risen from antiquarian book-pinching to ruthless murder.