2014: A great poem is read aloud and never heard again. For generations, people speculate about its message, but no copy has yet been found. 2119: The lowlands of the UK have been submerged by rising seas. Those who survive are haunted by the richness of the world that has been lost. Tom Metcalfe, a scholar at the University of the South Downs, part of Britain's remaining archipelagos, pores over the archives of the early twenty-first century, captivated by the freedoms and possibilities of human life at its zenith. When he stumbles across a clue that may lead to the great lost poem, revelations of entangled love and a brutal crime emerge, destroying his assumptions about a story he thought he knew intimately. A quest, a literary thriller and a love story, What We Can Know is a masterpiece that reclaims the present from our sense of looming catastrophe, and imagines a future world where all is not quite lost.