Synopsis

A deep dive into the Boston Marathon bombing investigation features Scott Pelley's interview with Boston Police Commissioner Ed Davis. Lara Logan gains exclusive access to the clandestine world of specialized canine units, some of whose skills remain confidential. Lesley Stahl secures an unprecedented preview of the National September 11 Memorial Museum, a vast subterranean space being constructed seven stories beneath ground zero. She tours the expansive facility, explores its planned exhibits,