We are familiar with the idea of our body’s biome – the bacterial fauna that populate our gut and can so profoundly affect our health. The next frontier of scientific understanding is discovering our body’s electrome. Every cell in our bodies – bones, skin, nerves, muscle – has a voltage, like a tiny battery. This bioelectricity is why our brains can send signals to our bodies, why we develop the way we do in the womb and how our bodies know to heal themselves from injury. When bioelectricity goes awry, illness, deformity and cancer can result. But could there be an undo switch for cancer to flip malignant cells back into healthy ones; the ability to regenerate cells, organs, even limbs; to slow ageing?

The science writer explores the history of bioelectricity, from Galvani’s epic 18th century battle with the inventor of the battery, Alessandro Volta, to the medical charlatans claiming to use electricity to cure pretty much anything, to advances in the field helped along by the unusually massive axons of squid.