In one of the most iconic scenes of The Graduate, Dustin Hoffman’s young character, Benjamin Braddock, gets some unsolicited investment advice from a family friend: "plastics.”

Replay that scene today and feckless Benjamin might hear a different word: magnets. In recent years, the humble magnet has become utterly essential to a number of modern industries, from electric vehicles to wind turbines. It’s a high-tech building block upon which fortunes will be made.

The little-known story of how magnets came to conquer the world is about more than exotic metals and cutting-edge research. Increasingly, it’s the tale of geopolitics, with growing tensions between China and the United States a central part of the story.