The Sigma Protocol Robert LudlumAmerican 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 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