March 1812 - A Swedish fishing vessel sets sail from the Polish port of Danzig (Now Gdansk) en-route for the Swedish mainland. On board, two French naval spies liaise with the boat's skipper over their mission, to spy on the British garrison stronghold on Hanö Island in preparation for a fully-fledged French invasion.

The island of Hanö (pronounced Haner), located off the southern coast of Sweden, is home to a flotilla of British warships whose job it is to keep the Baltic shipping lanes open and engage any French vessels it may come across. Frustrated and angered by constant British successes at sea, the French have drawn up secret plans for an all-out attack on the island's stronghold.

Arriving on the island, the two agents link up with Napoleon's spy master, a local Swede, who has been selected to oversee their mission and keep them hidden in his cabin deep in the heart of the island's extensive forest. Whilst patrolling the sea lanes Captain James Carey, commander of His Majesty's Royal Navy frigate HMS Hector, sights a French brig sailing northwards towards the Swedish coast. On engaging the French ship, the brig strikes her colours and surrenders after Hector's first salvo. The French captain is killed and on questioning the only officer of the brig left alive, James becomes suspicious believing he is not what he claims to be. Further questioning of the French lieutenant convinces the English captain that he is a spy and holding vital information pointing towards an imminent French attack on the British island garrison.

A chance encounter at sea with Anna, the beautiful daughter of the fishing boat's skipper, leads James into a passionate affair where he discovers fate waiting to deal an unforeseen hand.