As The Observer once put it, an abiding theme of Adam Curtis's documentaries "has been to look at how different elites have tried to impose an ideology on their times, and the tragicomic consequences of those attempts". This neatly sums up the essence of Curtis's new three-part series - though it looks like being more tragic than comic - which began with a daring parabolic narrative which soared from the monomaniac philosophies of Ayn Rand across California's Silicon Valley to the Clinton White House and Alan Greenspan's basilisk-like reign on Wall Street.