At the start of “Area 51,” Annie Jacobsen’s cauldron-stirring book about America’s most mysterious military installation, Ms. Jacobsen offers a passing glimpse of a large-headed little gray space alien being interrogated by scientists in white coats. This is both a tease and a distraction. Yes, Ms. Jacobsen will eventually address the U.F.O. issue with which conspiracy theorists eagerly associate Area 51, but her book is not science fiction. It’s much more levelheaded. It is an assertive account, revelatory but also mystifying, of the long-hidden United States weaponry and espionage programs to which she says Area 51 is home. (Some say Area 51 is home to nothing, because it does not officially exist.)To read the rest of the review, click here.