Caldwell frames the issue of Muslim immigration to Europe as a question of whether you can have the same Europe with different people. The author, a columnist for the Financial Times and a senior editor at the Weekly Standard, answers this question unequivocally in the negative.

He offers a brief demographic analysis of the potential impact of Muslim immigration—estimating that between 20% and 32% of the populations of most European countries will be foreign-born by the middle of the century—and traces the origins of this mass immigration to a postwar labor crisis. He considers the social, political and cultural implications of this sea change, from the banlieue riots and the ban on the veil in French public schools to terrorism across Europe and the question of Turkey's accession to the E.U. Caldwell sees immigration as a particular problem for Europe because he believes Muslim immigrants retain a Muslim identity, which he defines monolithically and unsympathetically, rather than assimilating to their new homelands.

This thorough, big-thinking book, which tackles its controversial subject with a conviction that is alternately powerful and narrow-minded, will likely challenge some readers while alienating others.

'Caldwell compiles his arguments patiently . . . with lucidity and intellectual grace and even wit. . . . He is a vivid writer, and like an action-movie hero he walks calmly away from his own detonations while fire swirl behinds him. . . . Mr. Caldwell’s book is the most rigorous and plainspoken examination of Muslim immigration in Europe to date, a sobering book that walks right up to, if never quite crossing, the line between being alarming and being alarmist. . . . Well-researched, fervently argued and morally serious . . . it may serve as a wake-up call to many of Europe’s liberal democracies.' The New York Times

'Caldwell knows Europe, especially France, better than most American and British commentators. . . . He is very good at pinpointing denial and flight from reality. . . . If his book sharpens a so far sluggish debate, it will have served an important purpose.' The Guardian