Gregg Wallace helps to unload a tanker full of sugar from Norfolk and follows it through one of the oldest sweet factories in Britain to see how over 500 workers, as well as some mind-boggling machines, transform it into over a hundred million individual sweets within just 24 hours. He discovers how the factory that produces Lovehearts could be the most romantic in the world because one in four of the people who work there are in a relationship with each other, how they make 5,000 Fizzers a minute using a tablet-pressing machine that uses 3 tonnes of pressure to create each sweet, and meets the man in charge of making three quarters of a million Fruity Pop lollies every day.Meanwhile, Cherry Healey is let inside the research and development department and experiences for herself how hard it is to come up with a new product, as she attempts to invent her own version of sherbet using citric acid and sodium bicarbonate. She also finds out how they put the letters in seaside rock by making a giant version and then stretching it to the right size, and is given special access to the Fisherman's Friend factory in Lancashire to discover how a local family turned a niche product into a worldwide success.And historian Ruth Goodman investigates how sweets were first invented and discovers that, in the Middle Ages, they were used as a medicine and thought to reduce flatulence. She also finds out about the human cost of Britain's sweet tooth in the 18th century and how an abolition movement instigated a sugar boycott which helped to end the slave trade.