"What they're going to do, I never would have believed it. It's insanity!" They were the final words spoken by Yuri Danko, an officer in the medical division of Russia's security service, before his body was ripped apart by a spray of assassins' bullets. In possession of Danko's classified papers, Covert-One operative Jon Smith and CIA undercover agent Randi Russell have unearthed a terrifying global conspiracy that threatens to unleash a plague of immeasurable proportions. A Serb terrorist has been dispatched from Russia to spirit hazardous vials of deadly bacteria into the United States. His mission: deliver it to an unknown American government agent-- a shadowy figure whose own motives for acquiring the bioweapon are made all the more unfathomable when both men are found murdered, and the strain is stolen. Now Smith and Russell must track it down, find the madman who possesses it, and stop him before he holds a defenseless world hostage with the power to render the human race extinct.
Nicholas Bryson spent years as a deep cover operative for the American secret intelligence group, the Directorate. After critical undercover mission went horribly wrong, Bryson was retired to a new identity. Years later, his closely held cover is cracked and Bryson learns that the Directorate was not what it claimed - that he was a pawn in a complex scheme against his own country's interests. Now, it has become increasingly clear that the shadowy Directorate is headed for some dangerous endgame - but no one knows precisely who they are and what they are planning. With Bryson their only possible asset, the director of the CIA recruits Bryson to find, reinfiltrate, and stop the Directorate. But after years on the sidelines, Bryson's field skills are rusty, his contacts unreliable, and his instincts suspect.
With everything he thought he knew about his own life in question, Bryson is all alone in a wilderness of mirrors - unsure what is and isn't true and who, if anyone, he can trust - with the future of millions in the balance.
Ben Hartman is vacationing in Zurich, Switzerland when he chances upon his old friend Jimmy Cavanaugh—a madman who's armed and programmed to assassinate. In a matter of minutes, six innocent bystanders are dead. So is Cavanaugh. But when his body vanishes, and his weapon mysteriously appears in Hartman's luggage, Hartman is plunged into an unfathomable nightmare...
Meanwhile, Anna Navarro, field agent for the Department of Justice, has been asked to investigate the sudden, random deaths of eleven men throughout the world. The only thing that connects them? A secret file, over a half-century old, that's linked to the CIA—and is marked with the same puzzling codename: Sigma.
As Anna follows the connecting thread—and Hartman finds himself on the run—she ends up in the shadows of a relentless killer who is one step ahead of her...victim by victim. Now, she and Hartman together must uncover the diabolical secrets long held behind Sigma. It will threaten everything they think they know about themselves—and confirm their very worst fears...
American investment banker Ben Hartman arrives in Zurich for a ski holiday, the first time he's been back to Switzerland since his twin brother died there in a tragic accident four years earlier. But his arrival in Zurich triggers something far more sinister than his brother's fate. When Ben chances upon Jimmy Cavanaugh, an old college friend, Cavanaugh promptly pulls out a gun and tries to kill him. In a matter of minutes, several innocent bystanders are dead - as well as Cavanaugh - and Ben has barely managed to survive. Plunged into an unspeakable nightmare, Hartman suddenly finds himself on the run.
Department of Justice field agent Anna Navarro is being stalked around the world by a relentless killer, managing to survive the killer's attacks only by a combination of luck, skill and her own quick wits. These attacks are somehow related to her current assignment: investigating the sudden - and seemingly unrelated - deaths of a number of very old men throughout the world. The only thing that connects them is a file in the CIA archives, over a half-century old, marked with the same puzzling code word: SIGMA. But someone or something is always seemingly one step ahead of her, the survivors are rapidly dwindling, and her own life is in ever increasing danger.
Brought together by accident, Ben and Anna soon realize that their only hope of survival lies with each other. Together they race to uncover the diabolical secrets long hidden behind the code word, Sigma. Secrets that threaten everything they think they know about themselves, everything they believed true about their friends and families, and everything they were ever taught about history itself. For behind Sigma lies a vast deception that is finally coming to fruition and the fate and future of the world is in their hands.