Downfall by Jeff Abbott
Sam Capra is hoping for a quiet life when he leaves the CIA and starts running a chain of bars.
Despite only being in his 20s, he has had a hard life and wants nothing more than to bring up his son in peace.
But that new peaceful life is shattered when a desperate young woman comes into his San Francisco bar looking for help.
The woman is being followed by two men who try to kill her, and so begins Sam’s involvement in a criminal underworld that gets shadier with every plot twist. He uncovers a gang of assassins, America’s high-flying business people run by an ice-cool boss.