Traveling to Earth after his trip to the core of the Milky Way Galaxy, Beowulf "Bey" Shaeffer befriends Gregory Pelton, a fabulously wealthy and gregarious flatlander who calls himself Elephant. Irritated at always being labeled a flatlander despite having logged many hours in space, Elephant decides to visit the most unusual system in or near Known Space, and has his agents put in a call to meet with the nearest Outsider vessel. Elephant, as well as two women named Diana and Sharrol, show Shaeffer around Earth for a few days; Shaeffer and Sharrol quickly develop a romantic relationship. Four days after landing on Earth, Elephant and Shaeffer travel to the edge of Known Space in Elephant's ship, the Slower Than Infinity, to meet the Outsiders for information on the location of the most unusual system in Known Space. The Outsiders charge a million "stars" for the whereabouts of the system and Elephant accepts; the Outsiders also offer to explain, for an additional two hundred thousand stars, what exactly makes the star system unusual. Elephant declines when they reveal that he will be able to find this out for himself. The Outsiders ferry the Slower Than Infinity to the system. The two make a list of particularities apparent about the planet orbiting what Shaeffer dubs the Fast Protosun:
Velocity of the system relative to Known Space, 0.8 c .
Possible extragalactic origin.
Only protostar in Known Space.
Extremely high radiation levels, which would result in their suit shielding breaking down in 3 days, the extension bubble in 20 hours.
The planet has no lithosphere, it appears to be worn down to the asthenosphere which has hardened in the interstellar cold.
An asteroid crater was nearly eroded away from interstellar dust, which should be too thin to work so fast.
There are helium II lifeforms present on the planet.
The lifeforms are all on the back side of the planet relative to its course through Known Space, as if they feared the interstellar dust.
The so-called "indestructible" General Products hull evaporates while within its vicinity.
Endangered by the final peculiarity, they only have just enough time to get their helmets on. The remainder of the ship, along with the stowed extension bubble, is still intact. Elephant insists on attempting to land on the planet anyway but Shaeffer convinces him that, unless he can explain why the General Products hull disappeared, they should run for it. Elephant agrees, resentfully, but says that if he were alone he would go down. With some difficulty, they return to Jinx. Most of the trip is made in silence as Elephant is not happy about running. Shaeffer gets in contact with a General Products puppeteer, declaring that his GP hull failed. He gives the puppeteer details about their exploration of the fast protosun and the puppeteer agrees to pay the indemnity, noting that they were unaware that such quantities of antimatter were present anywhere in the galaxy. This, the puppeteer explains, is what caused the hull to evaporate. It is thus revealed to Shaeffer and Elephant that what made the system the most distinctive was its composition: antimatter, which General Products hulls are not resistant to. Elephant finally understands why he’s just a "flatlander": He does not instinctively recognize that the universe is a dangerous place to live.
