In the '70s and '80s, “The Tonight Show” host Johnny Carson was the country's highest-paid entertainer and its most enigmatic. He was notoriously inscrutable, as mercurial (and sometimes cruel) off-camera as he was charming and hilarious onstage. During the apex of his reign, Carson's longtime lawyer and best friend was Henry Bushkin, who now shows us Johnny Carson with a breathtaking clarity and depth that nobody else could.