September 1810. British forces have used the utmost secrecy and stealth to cross the Straits of Messina and infiltrate the enemy's stronghold. Their mission: to disrupt preparations for the French invasion of Sicily. But when the raiding parties are ambushed by rival soldiers and suffer heavy casualties, one bright young officer suspects that treachery is involved. Ordered to investigate, George Warne uncovers a shadowy underworld of spies, traitors and informers, and where nothing is quite as it seems. Danger lurks around every corner and time is running out for Warne to root out the conspiracy. For how can Sicily's defenders be ready to repel an invisible enemy within?