Headphones: these marvels of miniaturisation are worn by over 30 million people in the UK. Hannah Fry visits legendary headphone honchos Bose to find out how today’s teeny earbud tech works and meets the human testers with ‘golden ears’. She discovers how helicopters in the Korean War helped put the ‘shhh’ into noise-cancelling, why it took a muted Mormon church service to get headphones onto people's heads, and how an opera singer’s electric shock therapy led to the invention of the speaker.

Hannah Fry discovers the hidden WWII radar technology that heats up baked beans, learns the legend of the melted candy bar in an engineer’s pocket that kick-started a kitchen revolution and puts her life on the line to demonstrate why microwaves zap food but not people.

With over six billion of them across the planet, smartphones have changed the modern world. With rare access to electronics giant Samsung, Hannah uncovers the technological game changers that have made the smartphone a reality. She finds out how a 1940s comic book hero inspired the first mobile phone, discovers why the invention of the digital camera led to one of the biggest commercial blunders of all time and reveals what a 2010 South Korean sausage frenzy can tell us about touchscreens.

Hannah takes a look at the vacuum cleaner, going behind the scenes with Dyson and discovering how the motor in their latest vacuum spins nine times faster than that of a Formula One race car. She finds out why a wheezy janitor in the 1900s took inspiration from a sewing machine to create the first popular portable vacuum. And she comes face to face with a colony of creepy crawlies whose job is to help us fight the filth.

Hannah gains access to a top-secret site where anonymous staff and the latest tech work to make the British passport one of the most secure documents on the planet. She reveals the World War I spy craft hidden in the pages of every passport and takes a look into how modern ID checks were shaped by the hunt for a 19th-century French serial killer and 1970s psychedelic art.