Right now, spacecraft are circling Mars, sweeping over Terra Sabaea, Syrtis Major, the dunes of Elysium and Mare Sirenum - on the brink, perhaps, of a discovery that would inspire humankind. With poetic precision, Sarah Stewart Johnson traces the evocative history of our explorations of Mars, interlacing her personal journey as a scientist with tales of other seekers who have scoured the planet for signs of life. Ultimately, she shows how its story is also a story about Earth: it is a mirror, a tell-tale reflection of our own anxieties and yearnings to find - if we're lucky - that we're not alone.