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.

The 8th episode reviews Giovanni Cassini's life. His observations of Saturn and its moons would have an enduring effect on the scientific world. Neil deGrasse Tyson also narrates the mysterious untold story of the scientist who figured out how to go the Moon while fighting for his life in a WWI trench. Aleksandr Shargei changed his name to Yuri Kondratyuk out of fear for his life and wrote a manuscript on rocket motion and space colonization. This letter would end up capturing the attention of an engineer working on the Apollo program, John Houbolt, and would made the Apollo Mission possible.
We will also know the saga of the twenty-year long odyssey of Cassini-Huygens spacecraft, a robotic explorer ordered to commit suicide on another world.

Dr Chris van Tulleken, Dr Hannah Fry and Michael Mosley examine the latest research and explore some of the big questions about Covid-19 and the pandemic it has created. Michael visits the UK government's high-security laboratory Porton Down, where vaccines are being tested. He also uncovers what the experience of the 2002 SARs epidemic reveals about this one. Both were caused by coronaviruses, but certain key changes to today's virus have allowed it to infect the world, where SARs was contained.

It's this moment where now both sides realize that no quarter will be asked, and no quarter will be given. Surrender is no longer even an option. You're in this to the end. You either die or you triumph, and there is no other alternative. Amid a spiral of brutality and low morale, Mehmed makes Giustiniani an enticing offer. The grand vizier urges Mehmed to seek a truce with his rival.

Hours before Mehmed II launches his final assault, an ominous sight shakes both sides. Rumors of a 40-ship fleet's imminent arrival have swirled for weeks, but it's exact whereabouts remained unknown. Ottoman cannons reduced the city walls to rubble, and Venetian reinforcements arrived too late. The conquest of Constantinople ushers in a new era for the Ottoman Empire, being a dominant force in world politics for 300 years. Mehmed II, in many senses, changed the nature of world history.

This second instalment looks at how Vladimir Putin arrived in the Kremlin as a vulnerable and unknown president, whom the Russian oligarchs expect to control. The programme reveals how he asserted his hold on power and ultimately surrounded himself with his KGB peers, as well as his philosophy as regards traitors and enemies. The film also examines the stories of businessman Boris Berezovsky and defector Alexander Litvinenko, who both stood up to Putin and wound up dead on British soil.