Sometimes it is impossible to tell just who is missing from a photograph—only that someone is. One photograph in King’s collection shows a propaganda train—a train that crisscrossed the country spreading the message of the revolution. “When we look closely at the window on the right of the photograph,” King writes, “a ghostly apparition—the result of the retoucher’s inept hand—is all that remains of the person who had been looking out of the carriage.” We don’t know who is missing or why—only that someone has been elided. We are lucky even to know that there is something we don’t know.

The October Revolution agitational-propaganda train arrives in Sorotskinskoe Station, in 1919. Photograph from Tate

There is so much more that we don’t know about Stalinist terror—we are no closer today to knowing how many people were killed than we were one, two, or five decades ago. Earlier this month, news came that the F.S.B., the successor agency to the K.G.B., is destroying secret-police records from the terror era; that means that we are unlikely ever to form a significantly more complete picture than the one we have now.

Many of the photographs in King’s collection showcase falsification by commission rather than omission. There is the iconic photograph of Stalin and the masses, in which the image of Stalin is blatantly pasted in, and the masses, less noticeably, are composed of several repeating fragments of crowd. There are the movie stills of the 1905 Russian uprising and the pictures of the storming of the Winter Palace, in 1917—in fact, the images depict historical reënactments that were used as though they were documentary photographs. And there are the enduring myths that underlie the images. Much of the absence of documentary evidence of the Soviet regime—the destruction of personal archives and printed books alike—was a result of citizens’ fear that their neighbors or acquaintances might report them to the authorities. We have since learned that the role of such denunciations during the terror was relatively minor: people were arrested to fill specific quotas; the arrests were essentially random and not, as many have long assumed, the result of reports. But the myth persists, and so does its product—the visuals that have been destroyed can rarely be restored.