Neutrinos are extraordinarily tiny particles (millions of times smaller than an atom) of which some 65 billion pass through every square centimeter of Earth each second. Because they are so small, the vast majority travel straight through the planet without even slowing down. But every once in a while, one collides with another particle and can finally be detected and analyzed. A visually stunning film that follows neutrinos from outer space to the three underground observatories where scientists attempt to study these intriguing particles.