Uki has lived a thousand million lives - perhaps even more. Her existence stretches so far beyond ordinary time that days, months, and years are meaningless; only the heaving of continents and the fury of tectonic plates are vast enough to measure her age.

But now, something is wrong. Where her soul once slipped effortlessly from one life to the next—between the final beat of one heart and the first beat of another—there are gaps. Vast, echoing chasms of nothingness are beginning to spread between her reincarnations.

To uncover the truth, she must track her way back through her own past. Back to the storm-lashed shores of Lake Geneva in 1816, beside Lord Byron and Shelley. Back to the silvered olive groves of 15th-century Tuscany under the watchful eyes of Leonardo da Vinci. She must face again the horrors of the First World War, walk through the embers of the Great Fire of London, and witness Earth from orbit as the planet begins to overheat.

Civilisations scramble for mountaintops as melting ice caps swallow cities. The oceans swell, rerouting coastlines and overwhelming species after species until life itself is brought to its knees.

Only when Uki stands on the surface of the moon, looking down at the world’s ruin, does she understand why Leonardo once named her Salvatore Mundi—the saviour of the world he prophesised she would one day become.