It is about the life of a Christian English boy in the 11th century who journeys across Europe in order to study medicine among the Persians.

He teaches the boy how to juggle, to draw caricatures, to tell stories, to entertain a crowd, to sell the nostrum on which they make their living.

He meets a Jewish physician in Malmesbury who tells him of schools (Madrasahs) in Córdoba, Toledo, even in far-away Persia, where the medical and scientific learning of the Muslims is taught.

In a moment of epiphany, Rob decides that he shall take on the guise of a Jewish student, so that he can travel to Persia and study at the feet of Avicenna (Ibn Sina).

He also meets a young woman called Mary Margaret Cullen, who was traveling with her father, in search of superior Turkish sheep.

The pair falls in love and become occasional lovers, but as Mary, by her father, proposes marriage to Rob, he dismisses her, saying that he needed to study medicine and telling her all his plans.

Rob arrives in the city of Isfahan, in the heart of the Abbasid Caliphate (in present-day Iran), and tries to enter into the school of physicians there.

Comparable to a surgical residency or similar term of practicum, Rob goes to a war-torn (and plague-torn) land to practice his medical knowledge.

As she has nowhere to go, and once they seem to love each other, although she is Christian, they form a liaison, and are secretly wed. Mary doesn't deal well with the new city, as she is neglected for being red-haired.

Regardless of all, Mary gets pregnant and has the child while Rob is in India, acting as a doctor and for the first time touching a corpse's heart.

Rob, his wife and children flee the rape and pillage and make their laborious way back to England.

Rob struggles to locate his lost brothers and sisters, likewise to make his place amongst the terribly ignorant physicians of London.