Aging King George III of England is exhibiting signs of madness, a problem little understood in 1788. As the monarch alternates between bouts of confusion and near-violent outbursts of temper, his hapless doctors attempt the ineffectual cures of the day. Meanwhile, Queen Charlotte and Prime Minister William Pitt the Younger attempt to prevent the king's political enemies, led by the Prince of Wales, from usurping the throne.

The adventures of the eponymous Lovejoy, a likeable but roguish antiques dealer based in East Anglia. Within the trade, he has a reputation as a “divvie”, a person with an almost supernatural powers for recognising exceptional items as well as distinguishing genuine antique from clever fakes or forgeries.