Ivo looks as if the sea has repeatedly tried to take him and been forced to settle for his coat. He waits with his weight on the balls of his feet, heels barely touching the deck, as if feeling for a change in the ship's balance. When he moves, he takes short, exact steps and turns his whole body toward a sound instead of just his head. His blue coat is stiff with salt at the seams, and his cuffs are dark with oil. A brass instrument lens hangs at his throat; one lens has been replaced by a tiny polished shell. He is often mistaken for a man holding himself under perfect control until a ship begins to founder, when his movements become swift and frighteningly heedless.

Ivo performs stern confidence because he believes a captain's doubt can spread faster than fire. In ordinary company he is patient, almost fussy, and delights in a clever repair or an uncharted inlet. When a plan goes wrong, he becomes blunt and tightly controlled. When a ship sinks or someone is trapped below deck, that control can snap into a furious, single-minded attack. Once the danger passes, remorse makes him meticulous about rescue and repair, and he struggles to accept comfort.

Ivo Daran grew up repairing tide gauges and hull pumps in Basings, where his mother, Eeva, kept a small salvage shop. He learned to calculate currents before he learned to read well. His first great invention was a pressure bell that let divers work deeper among the reefs. The royal survey ship Regent's Measure seized his design, then used it to recover a wreck full of unpaid island taxes and weapons for an occupation fleet. Ivo signed on as the fleet's engineer, telling himself he could limit the harm. During a storm, his crew mutinied against the officers and tried to surrender the ship to the island rebels. The officers retaliated. Ivo's wife, Anja, and their young son, Jori, were killed in the fighting, along with most of the crew he had grown up with. In the chaos, Ivo set the pressure bell's safety valves wrong and sank the ship. He survived with a handful of sailors, but the wreck became his private proof that cleverness could be as lethal as a blade. Now he captains the salvage sloop Sump, named after the flooded excavation where its hull was found. His crew raids imperial transports, frees pressed sailors, and dives the wrecks left by the Basings fleet. Ivo's old friend, Tamas, a former shipmate now working as a royal harbor inspector, tracks him through the islands. Ivo wants to stop the empire's coastal seizures, but he also keeps hunting for the surviving officer who ordered the mutiny's executions. He fears that revenge has become the only thing he is still good at.