All the Names by José Saramago

Senhor José is a lonely civil servant who spends his days labouring in the labyrinthine stacks of Lisbon's central registry. Among the file-cards for the living and the dead, one – of an apparently ordinary woman – will transform his life. Breaking away from his strict routine, José resolves to track the woman down, obsessively following a thread of clues in a bid to rescue her from an oblivion deeper than the grave.