The Power of Nightmares began as an investigation of something else, the rise of modern American conservatism. Curtis was interested in Leo Strauss, a political philosopher at the university of Chicago in the 50s who rejected the liberalism of postwar America as amoral and who thought that the country could be rescued by a revived belief in America's unique role to battle evil in the world. Strauss's certainty and his emphasis on the use of grand myths as a higher form of political propaganda created a group of influential disciples such as Paul Wolfowitz, now the US deputy defence secretary. They came to prominence by talking up the Russian threat during the cold war and have applied a similar strategy in the war on terror.

As Curtis traced the rise of the "Straussians", he came to a conclusion that would form the basis for The Power of Nightmares. Straussian conservatism had a previously unsuspected amount in common with Islamism: from origins in the 50s, to a formative belief that liberalism was the enemy, to an actual period of Islamist-Straussian collaboration against the Soviet Union during the war in Afghanistan in the 80s (both movements have proved adept at finding new foes to keep them going). Although the Islamists and the Straussians have fallen out since then, as the attacks on America in 2001 graphically demonstrated, they are in another way, Curtis concludes, collaborating still: in sustaining the "fantasy" of the war on terror.

• Part 1: Baby Its Cold Outside
• Part 2: The Phantom Victory
• Part 3: Shadows in the Cave