In this revealing and richly researched account, Alden describes how the Bush administration came to rely on the blunt instrument of immigration enforcement to carry out its counterterrorism strategy after 9/11. He shows how that approach exacerbated the dysfunction in long-neglected border-control systems, so that it is now somewhat more difficult for terrorists to enter the country -- and vastly more difficult for countless good guys whom the United States should welcome. Soon after the attacks, Attorney General John Ashcroft and his team, lacking intelligence on the movements of foreign terrorists, opted for a "spit on the sidewalk" plan of apprehending suspects for minor violations of immigration law. Over time, pragmatists such as Secretary of State Colin Powell and Homeland Security Secretary Tom Ridge, keen to preserve the economic and diplomatic benefits of smooth-flowing trade and travel, lost round after round to Justice Department and immigration officials who favored the prolonged detention of suspects, increased visa scrutiny, the registration of Muslim immigrants, and border fences. Alden tells of surgeons, aids researchers, physicists, and other world-class minds from places such as China and Pakistan who were humiliated, detained, or rejected by U.S. authorities. He oªers a detailed, evenhanded narrative of the fall of Ambassador Mary Ryan, a loyal diplomat who was sacrificed by the State Department after a number of 9/11 visa debacles came to light. Although he praises some post-9/11 measures, such as improved terrorist watch lists and the advanced screening of airline passengers, Alden argues that counterterrorism is a fine intelligence task that should be separated from the broad strokes of border and immigration control. He does not emphasize the problem of the 11.9 million illegal immigrants living in the United States, but it is hard to see how security can be achieved while so many dwell in the shadows.