Josh Hartnett to Headline Sky Original Series 'The Fear Index,' Based on Robert Harris Novel Naman Ramachandran, provided by FacebookTwitterEmail “Penny Dreadful” actor Josh Hartnett will star in Sky original thriller series “The Fear Index,” based on the bestselling novel by Robert Harris (“Fatherland”). Hartnett will star as Dr Alex Hoffman, a computer scientist and genius who is ready with a new AI product launch that promises big returns, but whose roll-out plans go awry. What follows is a journey through the worst 24 hours of his life — cutting across reality, memory and paranoid fantasy, forcing him to question everything he sees with his own eyes.