Alan Cumming's father Alex was a man who held his family hostage, who meted out violence with a frightening ease. Alex was the dark, enigmatic heart of Cumming family life. But he was not the only mystery. Alan's maternal grandfather, Tommy Darling, had disappeared to the Far East after the Second World War. Curious to explore this mystery, Alan committed to filming an episode of the BBC's Who Do You Think You Are? Then out of the blue, his father called. He had a secret he had to share.