The long winter is over in Helsop. Esme and Dag celebrate Dag's seventeenth birthday with a hunting foray into Helsop's old growth forest. Dag is delighted with Esme's gift. But when they return to the village with venison for the communal kitchen, Esme receives a mysterious summons to return at once to Henge.

The summons is brief and vague. Might it have to do with a marriage offer from Constantinople? Against her instincts, Esme knows she has no choice but to return home.

Meanwhile, in Henge, trouble is brewing. Pirates have attacked a ship loaded with guano bound for Henge and taken the co-captains, Cosmos and Alekos, prisoner. Henge must retaliate.

Soldad de Medich arrives from Constantinople with the worst possible news. His city is under siege from their neighbors the Ottomans. He needs weapons immediately – especially the dreaded Greek fire if it is available.