The Overloaded Ark

Orig. “The Entrance”, short story, 1979.

One day, a young man approaches a well-known antiquarian and asks him to catalog the contents of his home library. Soon the two of them become fairly close friends. But the young man has a family secret involving his old uncle and… mirrors. The mirrors hung in the uncle’s large house hide a terrible secret. And soon enough, someone will lift the veil of this secret—a secret that is better not to reveal.