The short story "Lefty" begins with the Emperor of Russia, Alexander Pavlovich, touring Europe with his companion Don Cossack Platov.

For his part, Alexander is intrigued by everything Europe offers, particularly England. Meanwhile, Platov tries his best to turn his sovereign's attention back to Russia.

The English, realizing that Alexander is fascinated by foreign inventions, invites the Russian emperor to tour London's factories and museums. They show Alexander their military arms inventions with pride. However, Platov puts a dent in their exultations by pointing out that one of the prized pistols on display is actually crafted by a Tula (Russian) craftsman.

Not to be deterred, the Englishmen later present Alexander with the gift of a steel flea (nymphosoria) that can execute elegant dance steps. One only has to turn a small key in the stomach of the flea to make the nymphosoria dance. The tiny key, however, is almost invisible to the human eye, so Alexander has to utilize a meagroscope to handle it.

The Russian emperor is so pleased with the gift that he orders Platov to pay the Englishmen lavishly. Alexander maintains that no Russian craftsman can surpass an English one. However, his sentiments offend Platov greatly.

In due time, Alexander dies and is replaced by his brother, Nicholas I. The latter inherits the nymphosoria but can make nothing of it. Equally flummoxed, the courtiers summon Platov, who explains everything to Nicholas. For his part, Platov encourages Nicholas to see if Russian craftsmen can surpass the accomplishment of their English counterparts.

Nicholas agrees and puts Platov in charge of the efforts. For his part, Platov hires three Tula craftsmen who promise to come up with something better.

The craftsmen remain vague about what they will accomplish, but Platov puts his trust in them. By the time the craftsmen present their work, however, Platov is furious. It seems that the flea shows no change in its anatomy. To teach the Tula workmen a lesson, Platov drags one of them (Lefty) to the palace to face the Emperor.

However, Lefty manages to acquit himself (and his fellow artisans) by asking Nicholas to examine each of the flea's feet under the meagroscope. When he does so, Nicholas sees that the Tula workmen have shod the English nymphosoria in horseshoes.

Additionally, each artisan has engraved his name on the shoe he fashioned. As for Lefty, he has made the greatest invention of all: the minuscule nails that hold the shoes in place. For those, there exists no meagroscope powerful enough to aid the human eye in seeing them.

Well pleased, Nicholas chooses Lefty to deliver the nymphosoria back to England. Once there, the Englishmen are so impressed with the new, improved flea that they offer to get Lefty trained as a master craftsman in England. For his part, Lefty is flattered but refuses. The only thing that impresses him about English craftsmanship is their seemingly superior way of maintaining the efficacy and condition of the nation's war weapons.

On his return home, Lefty gets into a drinking contest with an English bosun (boatswain or petty officer) who can speak Russian. Neither wins the contest.

Upon disembarking in St. Petersburg, Lefty is not recognized by the Russian officials. He ends up in a hospital of ill repute and eventually dies from exposure and substandard care. Before he dies, Lefty tries to get a Russian official to deliver a message to Nicholas: he wants the Emperor to know that the English don't clean their guns with bath brick.

However, the message is never delivered to Nicholas, as the officials don't trust Lefty, whom they consider to be a vagabond of sorts.

The story ends with the author mourning the loss of artisans such as Lefty. Today, machines have taken over what was once a master craftsman's domain—yet they can never produce the exquisite workmanship of past artisans.