HBO's 'The Cheshire Murders' explores the shades of gray in an open-shut case

The horrific July 2007 attack by two intruders on the Petit family (William Petit, his wife, Jennifer Hawke-Petit, and their daughters, Michaela and Hayley) at its Cheshire, Conn., home goes right to the essence of a core American fear, an abject anxiety that motivates some of us to buy alarm systems and handguns. Once in a while, evil really does come right through the front door, violating all sense of security, community and justice.