An accident at the Institute for Nuclear Research in Chicago releases a stray beam of radiation across the city, striking an innocent pedestrian by the name of Joseph Schwartz. No sooner does Schwartz step over a discarded rag doll on a busy street than he finds himself wandering for miles through dense woods.

Schwartz eventually stumbles onto a highway that leads him to a remote farmhouse where he seeks help, yet the residents do not understand a word of his frantic pleas. Despite their trepidation that he might be an “outsider,” they take him in for the night.

The next day, one of the farmers escorts a frightened and despondent Schwartz into the city of Chica where he is experimented upon using a device called the Synapsifier, which allegedly accelerates the human brain’s ability to learn. The machine is the invention of seasoned neurosurgeon, Doctor Affret Shekt who is assisted in his work by his daughter, Pola.

Schwartz quickly escapes from the hospital and slowly begins to develop the ability to read minds. Along the way, he becomes a fluent speaker of the native language and realizes that, somehow, he was hurled far into Earth’s future on that disorienting day in Chicago—a future in which the planet is a second-class member of a Galactic Empire!

It isn’t long before Schwartz finds himself embroiled with the Shekts and a brash archaeologist named Bel Arvardan from Sirius who visits Earth in an attempt to prove his theory that the planet is the origin of the human race. Together, the four uncover a conspiracy to destroy all life on the other planets in the Empire—but can they convince the authorities before it’s too late?

Pebble in the Sky is an engaging read, but it struck me that the protagonist, which one presumes to be Schwartz, becomes lost for several chapters as the other characters, especially Bel Arvardan and Pola Shekt, take prominence. It isn’t until his psychic ability fully manifests that Schwartz once again becomes crucial to the plot.

Further, the main villain in the conspiracy against the other planets is not revealed until the final quarter of the story. Before this, the character appears only briefly. Despite these observations, Pebble in the Sky is notable for its tangential place in the Galactic Empire of Asimov’s Foundation series.