Betrayals, confusions, ironies and disillusion aplenty run through this compelling look at lives by turns shaping or adrift within the political, cultural and social upheaval that was the '20th century'. The story starts in Republican Spain, with the extraordinary progress of Caridad Mercader, one time bourgeois housewife and then bohemian radical and KGB organiser. It was her son Ramon who plunged the ice pick into Trotsky's skull in Mexico. If there is a general absence of individual psychological analysis, it is chiefly because many of the lives examined are explained so much more effectively by 'history' and the times. That said, intriguing archive footage of Frida Kahlo and Diego Rivera, impressive talking heads including Trotsky's security guards, and powerful sidebars make for steadily fascinating viewing.