NOVA relates the 70-year struggle of scientists to understand neutrinos — mysterious ghostly particles that make up our world.

The cosmos has a secret ingredient: a swarm of invisible particles that fill every cubic inch of space. Trillions of them zip through our bodies, but we don't notice a thing. Yet without these ghostly, mysterious particles known as neutrinos, the sun wouldn't shine and the elements that make up our world wouldn't exist. NOVA tells the 70-year struggle of scientists to understand them, a tale of atom spies, secret laboratories and mind-boggling disappearances. This is the story of a discovery that changes scientists' understanding of what the universe is made of, and could bring us closer than ever to understanding how the universe was first formed.