Private Enquiry agent Cyrus Barker has just about seen it all -- he's been attacked by assassins, his office has been bombed, and evil-doers have even nearly killed his dog. But never before has a potential client dropped dead in his office. When Roland Fitzhugh, Member of Parliament, arrives to consult Barker and his partner Thomas Llewelyn, he falls to the floor, dead, upon entering. As they soon learn, he's been poisoned with a cyanide laced raspberry tart, and the adulterated tarts also take out an entire family in the East End. Labelled the Mad Pie Man by the press, Barker and Llewelyn are hired by former Prime Minister William Gladstone to find out who has targeted the House of Commons's newest member.