After a daring attack on the British collier fleet in the mouth of the Tyne River, Geoffrey Frost, merchant mariner turned reluctant privateer, returns to Portsmouth, New Hampshire in November 1776. There he learns that the war for independence has not gone well for the colonies. George Washington has been dislodged from New York, and the remnants of the Continental Army are being pursued across New Jersey by the British.

Knowing that the food and gunpowder he has captured from British supply ships are badly needed by the army, Frost resolves to carry the supplies to Washington. But the Royal Navy controls the coast from New York to the Chesapeake, so Frost must organize a complex and dangerous overland mission. Despite opposition from both loyalist militia and British patrols, the reluctance of his hastily conscripted army of teamsters, and the challenges of travel in the dead of winter, Frost wins through to the Continental Army in late December.

With his soldiers fed and their ammunition replenished, Washington leads a daring and brilliant night-time crossing of the Delaware River, and Frost and his men join the Continental Army in their surprise attack on the British at Trenton. With the timely assistance of Geoffrey Frost, Washington wins a victory that breathes new life into the Americans' resolve to win their independence.