A secret treaty will determine whether England can survive against Napoleon-Captain Grey races across the Atlantic to intercept a Spanish treasure fleet. Vienna-June 1804. At the glittering debut of Beethoven's Eroica Symphony, a Spanish diplomat meets with Captain Thomas Grey, agent of His Majesty's Secret Service. In exchange for a gigantic bribe, the Spaniard discloses Spain's most closely-held secret, the terms of its San Ildefonso Treaty with France. Spain's neutrality in Napoleon's war on Britain is only a ruse to keep the British navy from attacking the last great treasure-armada, now gathering in South America. Spanish warships will depart the port of Montevideo carrying 2,000 tons of gold; when the gold is safely in Madrid, Spain will declare war on Britain, ally with France, and divide the British Empire between them. Britain's only hope is a preemptive strike-to cripple Spain by capturing the armada on the high seas. The responsibility of delivering that blow falls to Grey.