Deep in the twisted roots of a giant strangler fig tree, hidden from view, lives perhaps the most bizarre nighttime creature of all. The spectral tarsier, tiny primates barely larger than a tennis ball. As darkness falls, a family of these small primates in Sulawesi ventures into the jungle to find food while protecting their babies.

April 1453. Sultan Mehmed II unleashes an artillery attack on Constantinople unlike any the world has ever known. It's the largest concentration of cannons that the world had seen in one place. The monumental task of keeping the Ottomans out of Constantinople falls on the shoulders of Genoese soldier of fortune Giovanni Giustiniani. He and his men must defend 14 miles of city walls. Mehmed launches his ambitious plans to break through the walls of Constantinople, but Giustiniani's mercenaries manage to forestall the attacks.

Mehmed II sends his elite troops into the teeth of Emperor Constantine's defenses along the city's ancient stone walls. The defenders, led by Italian soldier-of-fortune Giovanni Giustiniani, repel every attack. Mehmed's men dig underground tunnels in an attempt to shatter city walls. The tides turn against the Ottomans when a naval blockade founders.

Sultan Mehmed II's siege of Constantinople enters its third week. Mehmed's artillery teams continue their relentless bombardment of Constantinople's walls. After his navy suffers a devastating defeat, Mehmed moves his ships overland to the Golden Horn in a daring, visionary feat. In the shadow of betrayal, Giustiniani attacks the Ottoman fleet.

The fourth episode sees host Neil deGrasse Tyson exploring our eternal quest to end hunger and honoring Nikolai Ivanovic Vavilov, pioneer of modern plant breeding, who risked his life for a discovery that would change the history of science. Vavilov's story is marked by both the tenacity and creativity and is particularly tragic. Interwoven into Vavilov's somber narrative are warnings and treatments of science and its ethical implications, especially when science itself comes under attack from political forces.

We inhabit a cosmos of undiscovered dimensions and paradoxical realities. We live on one level of perception, but there are others. Every once in a while, a searcher happens upon the doorway to one of these other levels. One of them discovered a paradox about reality that proved to be so profound, we have yet to understand how it could be possible. The universe, or perhaps we should say, universes have never been the same.
In the counterintuitive realm of quantum mechanics, light can be two contradictory things, and somehow - no one knows how - an unseen observer can alter the nature of reality. The man who stumbled on this hole in reality and the still- unfolding technological revolution that it made possible.