This episodes the nature of the cosmos on the micro and atomic scales, using the Ship of the Imagination to explore these realms. Tyson describes some of the micro-organism that live within a dew drop, demonstrating parameciums and tardigrades. He proceeds to discuss how plants use photosynthesis via their chloroplasts to convert sunlight into chemical reactions that convert carbon dioxide and water into oxygen and energy-rich sugars. Tyson then discusses the nature of molecules and atoms and how they relate to the evolution of species. He uses the example set forth by Charles Darwin postulating the existence of the long-tongued Morgan's sphinx moth based on the nature of the comet orchid with pollen far within the flower. He further demonstrates that scents from flowers are used to trigger olfactory centers in the brain, stimulating the mind to threats as to aid in the survival of the species. Tyson narrates how Greek philosophers Thales and Democritus postulated that all matter was made up of combinations of atoms in a large number of configurations, and describes how carbon forms the basic building block for life on earth due to its unique chemical nature. Tyson explains on the basic atomic structure of protons, neutrons, and electrons, and the nature of nuclear fusion that occurs in most stars. He then discusses the existence of neutrinos that are created by these nuclear processes in stars, and that detecting such sub-atomic particles which normally pass through matter require subterranean facilities like the Super-Kamiokande that were used to detect neutrinos from the supernova SN 1987A in the Large Magellanic Cloud before light from the explosion were observed due to their ability to pass through matter of the dying sun. Tyson compares how neutrinos were postulated by Wolfgang Pauli to account for the conservation of energy from nuclear reactions in the same manner as Darwin's postulate on the long-tongued moth. Tyson concludes by noting that there are neutrinos from the Big Bang still existing in the universe but due to the nature of light, there is a "wall of infinity" that cannot be observed beyond.

Planets beyond our solar system are known to astronomers as exoplanets. They are at trillions of miles from Earth and yet, it might be possible to detect a faint signature of life in them. From the light of the stars they orbit that passes through the atmosphere of an exoplanet, it is possible to capture the chemical fingerprint of the elements in that atmosphere.
The fictional world Eden is orbiting not one star, but two. The light from its twin stars powers photosynthesis, pumping more oxygen into the atmosphere than in Earth, allowing life to thrive. Grazers are constantly alert to danger, because the canopy is home to predators perfectly evolved to live among the trees. In Episode 3, another topic are fungi and the role they could play on exoplanets. Ecologist Thomas Crowther talks about the role mycelial networks play in the Rothiemurchus forest in Scotland.

Oceans are the largest ecosystem on earth, covering two thirds of our world’s surface and providing half the oxygen in our atmosphere. They are home to as much as 80 per cent of all life on earth, and nearly three billion people rely on them for their primary source of food.
But our planet’s oceans would be little more than stagnant wastelands, and life on planet earth would cease to exist, were it not for one simple factor: a global network of powerful ocean currents. Every drop of seawater on earth rides these currents, taking 1,000 years to complete a single circuit. Without the constant mixing of currents, tides and waves, our oceans would stop supporting life - and a healthy ocean is vital to a healthy planet.

The cosmos, with its billions of galaxies and countless stars, isn't the only one. We share our lives with another universe: The world of the small, of the viruses, of the bacteria. We call this strange hidden kingdom the Microcosmos. We share our world with the microcosmos. Will we coexist in an uneasy peace, or will it destroy us?
In 2020, A tiny virus caused a global pandemic, COVID-19. This pandemic makes people see the world completely differently, because there was an invisible universe, pretty much ignored for the most part. Very, very tiny things have a huge impact on our lives. The microcosmos is complex, while some parts kill us, others keep us alive. The microcosmos is responsible for the very oxygen that we breathe and the soil on which we live. And it will influence our future as we venture out into space.

All of our pets survived for thousands of years in the wild without any help from us, and this has led them to develop astonishing athletic abilities which we sometimes take for granted. As greyster dogs and endurance champ tortoises.
Dog scootering uses one or more dogs to pull a human riding an unmotorized scooter. Greysters are a naturally-athletic breed that can run at 20 miles per hour for five miles while handling these carriages. No other animal can run at this speed, exerting this power, and expending this energy for so long. So, what's their secret? Greysters' stride length can be a staggering 16 feet and they are super efficient at absorbing and using oxygen. Greyster dogs have nearly twice mitochondria inside their cells than humans.