Throughout history, collaboration has fuelled greatness. From rivals pressuring each other forwards to friends combining their talents, it’s clear: often two heads are better than one. Cathy Newman rewrites the history books to expose this strange power of two – the reason Holmes and Watson need to come as a pair, and Apple could not have been started by Steve Jobs alone. Bringing together an extraordinary range of stories from around the world, Newman shows how double acts have relied on each other, how minds have married to usher in miraculous discoveries, and how those we think of as lone geniuses often did not work solo. Vibrant, feminist and unexpected, this brilliant history shows the value of friction, obsession, difference and trust when it comes to progress – and retrieves the work of many who have been forgotten, asking why certain collaborators are so often left out of the narrative. Previously published as ‘It Takes Two’.