July, 1806. Commanding a prison-hulk filled with French captives in the Medway, Martin Jerrold thinks his war can't get much better. He's far away from storm, battle and the other disagreeable elements of naval life. He can keep his mistress, Isobel, close at hand. It seems too good to last, and so it proves.

When one of the prisoners goes missing, Jerrold's comfortable world is turned upside down. Summoned to London by the First Lord of the Admiralty, he is ordered to recapture the Frenchman at any cost. Jerrold does not know it, but his pursuit will take him clear across England: from the stinking marshes of Chatham to the slums of London; from the wilds of Dartmoor to the newly fashionable seaside resort of Brighton.

But why is the prisoner so important? At the Post Office, Jerrold's old friend Mr Nevell is curious; so too are politicians from the highest levels of the Whig government, and the Tory opposition led by the cunning Spencer Perceval. Even the seductive Princess Caroline takes an unexpected interest.

As Jerrold - with his usual mix of bad timing, bad luck and bad behaviour - closes on his quarry, he begins to uncover an extraordinary tangle of deceit and treachery which stretches back over twenty years to the most exalted levels of society on both sides of the Channel, and which some men will stop at nothing to protect.