A cosmologist hosts this series on the biggest open questions in modern physics: whether the universe had a beginning, whether life exists elsewhere, what the cosmos will become, and what reality is actually made of. The opening episode, "Why Are We Here?", starts by dismantling a basic assumption: ordinary atoms, the stuff of stars, planets, and people, account for only about 15 percent of everything that exists. The rest is dark matter, mass that has never been directly seen but whose gravity holds galaxies together, and the episode lays out how astronomers inferred it exists without ever detecting it directly. Later episodes carry the same approach into cosmology's other unresolved problems, treating each answer as provisional and pointing to the next question it raises. There are no reenactments or field shoots here, mostly direct-to-camera explanation and diagrams, built around the idea that the universe's biggest mysteries are defined as much by what remains unknown as by what has been confirmed.