In an era when capitalism leaves so many to suffer and to die, with neoliberal 'self-care' offering little more than a bandaid, how can we take health and care back into our hands? In The Hologram, Cassie Thornton puts forward a bold vision for revolutionary care: a viral, peer-to-peer feminist health network. The premise is simple: three people - a 'triangle' - meet on a regular basis, digitally or in person, to focus on the physical, mental and social health of a fourth - the 'hologram'. The hologram, in turn, teaches their caregivers how to give and also receive care; each member of their triangle becomes a hologram for another, different triangle, and so the system expands. Drawing on radical models developed in the Greek solidarity clinics during a decade of crisis, and directly engaging with discussions around mutual aid and the coronavirus pandemic, The Hologram develops the skills and relationships we desperately need for the anti-capitalist struggles of the present, and the post-capitalist society of the future. One part art, one part activism, one part science fiction, this book offers the reader a guide to establishing a Hologram network as well as reflections on this cooperative work in progress.