Adam Lanza blasted his way into the Sandy Hook Elementary School. He fired a half-dozen thunderous rounds from a semiautomatic rifle to open a hole big enough to step through in one of the school's glass doors. Once inside, he had to make a choice. Principal Dawn Hochsprung's office was straight ahead. To the right, 25 or so children were rehearsing a play in the school cafeteria. To his left were the first-grade classrooms.