Mention Smaug, the classic storybook dragon of J.R.R. Tolkien's "The Hobbit," and a ray of delight flickers across Benedict Cumberbatch's pale eyes.

Smaug, "a most specially greedy, strong and wicked worm" of Tolkien lore, is for many children their first encounter with fire-breathing, scaly dragons. "First one for me," Cumberbatch is quick to add. "My dad read the book to me and it was a bedtime treat if I had done well. If I had been a good boy, I'd get two chapters as opposed to maybe...