An enigmatic flneur named Gaustine opens a "clinic for the past" that offers a promising treatment for Alzheimer's sufferers: each floor reproduces a decade in minute detail, transporting patients back in time. As Gaustine's assistant, the unnamed narrator is tasked with collecting the flotsam and jetsam of the past, from 1960s furniture and 1940s shirt buttons to scents and even afternoon light. But as the rooms become more convincing, an increasing number of healthy people seek out the clinic as a "time shelter" -- a development that results in an unexpected conundrum when the past begins to invade the present.