In an epic story of discovery, strong evidence is presented for a dead civilisation on Mars and the shocking reason for its demise: an ancient planetary-scale nuclear massacre leaving isotopic traces of vast explosions that endure to our present age. The story told by a wide range of Mars data is now clear. Mars was once Earth-like in climate, with an ocean and rivers and for a long period became home to both plant and animal life, including a humanoid civilisation. Then, for unfathomable reasons, a massive thermo-nuclear explosion ravaged the centres of the Martian civilisation and destroyed the biosphere of the planet. But the story does not end there. This tragedy may explain Fermi's Paradox, the fact that the cosmos, seemingly so fertile and with so many planets suitable for life, is as silent as a graveyard. We must immediately send astronauts to Mars to maximise our knowledge of what happened there and learn how to avoid Mars' fate. Includes an 8-page colour section.