This is the first biography of Capt. Joe Rochefort, the Officer in Charge of Station Hypo the U.S. Navy's decrypt unit at Pearl Harbor and his key role in breaking the Imperial Japanese Navy's main code before the Battle of Midway. It brings together the disparate threads of Rochefort's life and career, beginning with his enlistment in the Naval Reserve in 1918 at age 17 (dropping out of high school and adding a year to his age). It chronicles his earliest days as a mustang (an officer who has risen from the ranks), his fortuitous posting to Washington, where he headed the Navy's codebr