In Roald Dahl’s novel The Wonderful Story of Henry Sugar, what unusual ability does Henry learn?

In Roald Dahl’s The Wonderful Story of Henry Sugar, Henry learns the unusual ability to see through playing cards.

Henry encounters an account of an Indian man who can identify cards without looking at their faces. The ability is attributed to training associated with a yogi and is presented within a story-within-a-story structure.

At first, Henry wants to use the skill to cheat at casinos. After becoming extremely wealthy, however, he changes his purpose and secretly gives away his winnings to help children.

The title story was published in a 1977 collection. It is often remembered as a straightforward magic tale, but its frame narrative also explores greed, philanthropy and the moral consequences of using extraordinary knowledge.