Twenty stories comprise this collection of what Asimov himself considered his finest work up to 1969.  These tales had been originally published in such periodicals as Astounding Science Fiction, Galaxy Science Fiction, Playboy, Star Science Fiction Stories, Scientific American, and more.

My favorites include:

An advanced civilization panics when five of their suns have set and the sixth is about to be eclipsed, casting their part of the world into “Nightfall” for the first time in generations. Arguably one of Asimov’s best stories of all time.

To the chagrin of her police officer husband Drake, biologist Rose Smollett volunteers to play “Hostess” to an alien scientist from Hawkins’ Planet. It isn’t long before Drake discovers that the alien has ulterior motives, one that could ignite an interstellar war.

When a physicist named Ralson threatens to commit suicide, he is placed under psychiatric care by the Atomic Energy Commission with the caveat that any therapy must be quick. Ralson has the uncanny ability to rapidly solve almost any scientific problem and the A.E.C. thinks that he can create a force field to repel atomic energy. Of course, they want it done yesterday in “Breeds There a Man…?”

A merchant ship from Earth is captured by an alien enemy known as the Kloro. While the humans aboard are antagonistic toward one another, one man named Mullen rises above by volunteering for a dangerous mission. If he is successful, the other passengers will be able to retake the ship. Mullen must suit up and walk the exterior hull of the craft in magnetic boots, but to get there, he’ll have to be ejected from the corpse chute, otherwise known as the “C-Chute.”

Jeff Stock and Dick Altmayer have been friends for decades, during which Jeff has risen through the military ranks and Dick, a conscientious objector, has been arrested multiple times for draft dodging, terrorism, and treason. Yet, in the end, it’s possible that both men are heroes “In A Good Cause—”.

After discussing what might have happened if they’d each made different choices in life, a married couple named Norman and Livvy encounter a eccentric old man on a train who presents them with a mirror that allows then to ask “What If—” and see the results play out. Will Norman and Livvy’s love survive this test?

A con-man named Gellhorn visits a mechanic named Jake who restores old automatic cars and allows them to roam free on his farm. Gellhorn tries to make an offer that Jake cannot refuse—take parts from Jake’s restores and use them to refurbish old vehicles to sell at new car prices. After Jake turns him away, Gellhorn returns with muscle, but they are no match for “Sally“, Matthew, and the rest of the cars with minds of their own…

“It’s Such a Beautiful Day” when young Richard decides to walk to school after the teleportation “Door” in his home malfunctions. The problem is that in this perfect utopia, no one ever walks outside when you can simply use the Door system to teleport anywhere in the world. When Richard begins to form a habit of strolling outdoors at every opportunity, a psychiatrist is called in, but in the end, who ends up being the true counselor?

An elderly sociologist travels to the human asteroid colony of Elsevere to study their caste society. Upon arrival, he suspects something is wrong and is proven correct upon learning that the head of sanitation, who lives well and is highly compensated, is nevertheless treated like a second class citizen. No one else on Elsevere will even speak to Ragusnik or his family. As a result, Ragusnik has stopped work and in the end, it’s up to Lamorak to be the “Strikebreaker.”