American investment banker Ben Hartman - son of legendary Max Hartman, who built a financial empire up from next to nothing - is on holiday in Switzerland when he meets a childhood friend - who promptly tries to kill him. Narrowly surviving the attempt, Ben discovers that all evidence of the confrontation has disappeared. But this is only the beginning...Anna Navarro, a US government agent, is sent to surreptitiously look into a string of deaths of old men around the world. The only thing the victims have in common is an old OSS file, codenamed SIGMA. But as soon as she starts to get somewhere, she is dragged off the case and declared rogue. Someone wants this secret kept and not only the future of Hartman and Navarro is at stake, but that of the world...