When an entire family tragically vanished from a house down the street, Peter Lovenheim realized he hadn't known them or his remaining neighbors either. To the distress of his teen-age daughter — and his own surprise — many of them accepted when he asked to sleep over so they could get better acquainted. His book on what happened has reignited discussion about the increased fragmentation of American life and the broader issue of civic disengagement. Has real communication been replaced by communication technologies? Can a nation of people who don't know each other continue to stick together?