Around the world, food allergies are surging to near-epidemic levels. Medicine is just beginning to understand why some people react to seemingly harmless foods. Scientists race to understand what's changed in our bodies, while farmers and chefs contend with new challenges.

Autistic minds provide windows into how we all think, feel, and behave. A complete brain science should be able to account for all kinds of minds and brains. As long as some minds remain a mystery, so too will all minds.
Michael Stevens travels to London to meet a blind, autistic savant with astonishing musical abilities, and volunteers to have his brain's function temporarily disrupted at UCLA's Neuromodulation Lab.

The nervous system is fundamentally electric. When we move our arm, it moves because a electric signal has been sent to the muscle that controls it. Now, because the brain is electric, we could also use electricity to record what the brain is doing or bypass it entirely, and control a body. That means that we could restore movement to people who are paralyzed, feel through an artificial hand as if it was our own, and even read people's minds.
Michael Stevens explores how electricity can be used to move cockroaches, control other peoples' limbs and even read peoples' thoughts.

In the fifth episode Neil deGrasse Tyson explores questions that have baffled scientists for centuries. Can we know the universe? Are our brains capable of comprehending the cosmos in all of its complexity and splendor?. We don't yet know the answers because our brain remains almost as much of a mystery to that questions as the universe itself. An abandoned orphan's dream opened the way to understanding the architecture of thought.

In the second part and conclusion, a spotlight on the mass marketing of the synthetic opioid fentanyl examines the connections between drug manufacturers and government policy. Video of sales retreats and promotional material reveals a deep cynicism among company employees and a disregard for the widespread, nefarious corporate practices.

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.