Released in 1964, before the presidential election, the book went as viral as anything could in an analog age. We might think that by then the country had moved beyond the McCarthy era of the 1950s, with astronauts circling the globe, and polio and measles on their way to being eradicated with mass vaccination campaigns. But the Cold War was going strong.

That year, Mr. Hunt was a sophomore at Fordham Preparatory School in the Bronx. “When we were freshmen, one of the teachers told us that if communists invaded the United States, as members of the Catholic intelligentsia, we would be lined up and shot,” Mr. Hunt said. “So when the book came out the next year, it was a big item that a lot of kids were talking about.”

Mr. Stormer stuffed his tale of conspiracy with anecdotes and examples of what he said was communist infiltration of school boards, courthouses, the State Department and the White House. Franklin D. Roosevelt was quoted as saying that some of his best friends were communists, with the Congressional Record cited as the source.

Mr. Hunt said his English teacher, Lawrence Schaefer, had heard the chatter among the boys. They defended the reliability of the book by pointing to its 800 footnotes. “He brought us to the library,” Mr. Hunt said, and told the students to dig into the sources in the footnotes.

They soon found a dog chasing its own tail. The Congressional Record did, in fact, contain Roosevelt’s supposed remarks on his friends the communists. But it wasn’t quoting him; they were in an essay by a man Roosevelt had driven from office, and who did not reveal this supposed conversation for 12 years — after the deaths of all the other people he claimed had been present.