Agora is an insular city-state where anything can be bought and sold. Everything is a commodity; goods, services, people, thoughts, concepts and even emotions are bartered on the open market. It’s an economy without money, where trade is the only way of life and debt is death. The successful elite rule, plague festers in the pitiless slums, and children are possessions until their twelfth birthdays.

In the ancient tower of Count Stelli, the city’s greatest astrologer, two children meet, both of whom have been sold into servitude. Mark is an emotional, imaginative boy who is sold by his father to the Count’s grandson in return for medical treatment. The other child, Lily, is reserved and thoughtful; an orphan now owned by the Count. At first, threatened with being thrown out to die on the disease-ridden streets if they displease their masters, Mark and Lily’s only goal is to work and survive. However, as they begin to understand that they can shape their own destinies, they each find their own path — Mark within the system, angling for power and the security it brings; and Lily beyond it, determined to change the city forever. Unbeknownst to them both, however, Mark and Lily are watched by the mysterious ruler of Agora, the Director of Receipts, whose interest in the apparently insignificant pair is more than a passing one.