Gregg Wallace visits the colourful and fragrant Lush factory in Dorset to learn how an astonishing 14 million bath bombs are produced every year.Cherry Healey visits Loughborough University to learn how taking a hot bath can provide some of the benefits of exercise, and she visits a cutting-edge lab which grows human skin for cosmetic testing.Historian Ruth Goodman explores a time when complex perfumes were thought to ward off the plague and learns how the living conditions of coal miners and their families were transformed with the introduction of communal showers.