Steve McQueen’s “Blitz” follows the epic journey of George (Elliott Heffernan), a 9-year-old boy in World War II London, whose mother Rita (Saoirse Ronan) sends him to the safety of the English countryside. George, defiant and determined to return home to his mother and grandfather Gerald (Paul Weller) in East London, sets out on an adventure, only to find himself in grave danger when a distraught Rita searches for her missing son.