Physicist Jim Al-Khalili sets out to answer two questions that sound simple and turn out to be nearly impossible: what is everything, and what is nothing? The first part traces the size and shape of the universe, from Edwin Hubble's discovery that galaxies are racing away from us to the debate over whether space itself is infinite or merely unimaginably large. The second turns to the vacuum, following physicists who have spent careers trying to empty a box completely and finding that empty space still seethes with particles flickering in and out of existence, a consequence of quantum theory that Al-Khalili demonstrates with the Casimir effect. He talks to cosmologists and quantum physicists on location at observatories and laboratories, using models and simple demonstrations rather than dense equations to carry the argument. The two episodes work as a pair, one pushing outward to the edge of the cosmos and one pushing inward to the smallest possible scale, both arriving at the same unsettled conclusion: neither infinity nor nothingness behaves the way common sense expects.