American investment banker Ben Hartman -- son of the legendary Max Hartman, who built a financial empire from less than nothing -- is on a vacation trip to Switzerland when he is approached by a childhood friend, who promptly tries to kill Ben. Narrowly surviving the attempt on his life, Ben discovers that the body of his former friend -- as well as all evidence of the confrontation -- has disappeared. But the attempts against his life are just beginning.

Anna Navarro, a U.S. government agent, is sent to surreptitiously look into a string of deaths and murders of old men around the world. The only thing the men have in common is an OSS file marked with the code word SIGMA. But as she investigates, she suddenly finds herself pulled off the case, declared rogue by her superiors, and the target of an all-out manhunt.