After the devastating loss of Danny Devlin, the ECHO team regroup in Greece and prepare for the most important mission of their lives, but within minutes of their first briefing their world is once again shattered by the sniper fire of an unknown assassin who is hunting them one by one.With time against them, they must retrieve Alexander the Great’s Codex from the Oracle’s inner sanctum and only then will they have a chance of locating the ancient Citadel and discovering its many secrets. Meanwhile, the traitors in the heart of Washington DC work ceaselessly to get what they want and depose the US President from power in the most shocking takeover in American history.From warships in the Aegean Sea to warfare in the Malaysian jungle, and from Tokyo’s neon-lit underbelly to the casinos of Las Vegas and beyond, the team are engaged in their toughest and most challenging mission. Tested almost beyond their endurance, their struggles culminate in a savage endgame in the ancient Citadel and the arrival of a force of mysterious new warriors known only as the Guardians.As more members of the team fall victim to the Pentagon’s hidden assassin, new faces arrive just in time to fight alongside Joe Hawke and the rest of the team in this most epic of ECHO adventures.