In the autumn of 1523, Roger Shallot, self-proclaimed physician, rogue, charlatan and secret emissary of King Henry VIII, has nothing to do. His master, Benjamin Daunbey, has been sent to Italy on a diplomatic mission, leaving him in charge of their manor outside Ipswich. Shallot, forbidden both to practise the art of medicine and to approach the beautiful Miranda, takes to reading. Discovering the potential wealth which can be accrued by the finding and selling of true relics, he goes in search of his own. Almost immediately he is in trouble - and in prison.

Rescued by the return of his master and the influence of Cardinal Wolsey, Shallot finds himself at court, where he is ordered by King and Cardinal to break the law - to steal back for the crown the Orb of Charlemagne, now under close guard at the priory at Clerkenwell. Benjamin and Roger have no choice but to agree to the task.

Before long they are drawn, not only into the shadowy underworld of Tudor London and the illegal trade of relics, but also into murder and blackmail, as they race against time to find the Orb of Charlemagne and save their own necks.