The “enheimer” of Barbenheimer is giving moviegoers the cliff notes on how a Soviet spy ring infiltrated the Manhattan Project, stealing secrets of the atom bomb. (READ MORE: Barbie Questions the Success of Feminism)

Seventy-five years ago this month, another one-time spy was caught in a series of lies. The Hiss Case, as it became known, was a complicated back and forth of mystery, intrigue, revelation, misunderstanding, political chicanery, and even a suicide attempt.

On Aug. 3, 1948, Whittaker Chambers — a disheveled, unkempt Time magazine editor and former member of the Communist Party — appeared before the U.S. House Committee on UnAmerican Activities and accused well-established nonprofit executive and former diplomat Alger Hiss of being a Communist.

In and of itself, harboring communist sympathies is certainly not illegal. But distributing secret U.S. government documents to an adversarial Communist power certainly is illegal. And that’s what the HUAC and Truman Justice Department investigations would eventually expose: Hiss was part of a Communist spy ring that operated in the 1930s.

But things started slowly, as Chambers’ accusations — delivered under oath — failed to stoke a fire. The Aug. 3, 1948, hearing was uneventful until Hiss responded to Chambers’ testimony two days later. Besmirched, he was — or so he claimed. And he demanded to clear his name. (READ MORE: Whittaker Chambers’ Witness, 70 Years Later)

Hiss was president of the Carnegie Endowment in New York. He had advised and accompanied FDR to Yalta and had been a senior State Department official in the Truman administration.

With all the drama of a Hollywood movie, Hiss appeared before the committee and dazzled his national audience, forcefully, and effectively challenging the committee’s mandate, rejecting any connection to the Communist party and disavowing Chambers’ accusations.

“I’m afraid the committee has been taken in by Chambers,” Rep. Christian Herter said. Rep. Ed Hebert suggested the committee “wash our hands of the whole mess.”

But one committee member wasn’t convinced.

“[W]hile Hiss had seemed to be a completely forthright and truthful witness, he had been careful never to state categorically that he did not know Whittaker Chambers,” first-term Rep. Richard Nixon later wrote. “If Hiss were lying about not knowing Chambers, then he might also be lying about whether or not he was a Communist.”

Nixon began to dig. Chambers, as it turned out, possessed a photographic memory. Quizzed for hours by Nixon and his fellow HUAC members and investigators in executive session and later at his Pennsylvania farm, Chambers relayed in excruciating detail how well he knew not only Alger Hiss, but Mrs. Hiss — including their nicknames, hobbies, details of their home furnishings, and the kennel at which they boarded their cocker spaniel. (READ MORE on Richard Nixon: Don’t Blame Nixon for China’s Rise)

When asked by Nixon about his hobbies, Hiss ensnared himself in a trap by listing his fondness for birdwatching, becoming animated at having seen a rare prothonotary warbler — and confirming Chambers’ recollections.

The committee forced Hiss to confront Chambers, and it did not go well. Over the following weeks, Hiss’ gradually changing story and half-hearted denials eroded his once iron-clad credibility.

Public perceptions of Hiss also began to shift, as did the tone of the press coverage. President Nixon later said that the Hiss Case was won in the press. “I had to leak stuff all over the place,” Nixon told his chief of staff. “I played it in the press.”

Finally, the proof emerged in a pumpkin.

Faced with skepticism from the Truman Justice Department, Chambers attempted suicide before producing dozens and dozens of secret State Department documents from his own time spying for the Soviet Union.

As insurance against political interference, Chambers kept a cache of stolen documents in a dumbwaiter shaft in his wife’s nephew’s mother’s apartment building — and, more famously, stashed five rolls of microfilm for 24 hours in a hollowed-out pumpkin on his farm.  Many of these documents were later determined to have been typed on Hiss’s Woodstock typewriter.

These bombshells exposed Hiss as not only a one-time member of the Communist party, but party to a spy ring of U.S. government officials — including Assistant Secretary of the Treasury Harry Dexter White.

Amazingly, the statute of limitations on treason is only three years. So Hiss was instead indicted and tried on two counts of perjury. After a mistrial, he was convicted and sentenced to five years in federal prison, of which he served three years and eight months. He would live a quiet life as a salesman and author (and occasional political commentator, trashing Nixon in 1962 as part of an infamous and premature ABC News special “The Political Obituary of Richard Nixon”).

Whether the HUAC was a defender of the liberal constitutional order America’s Founders envisioned, or a mechanism to shred free speech by government sanction is still debated today, including in the new blockbuster Oppenheimer.

What should not be up for debate is Hiss’ guilt. Amazingly, some still remain unconvinced — but there is ample evidence gathered as part of the Venona project, as well as documents from the Soviet archives revealed during Russia’s flirtation with democracy in the 1990s.

Seventy-five years ago this month, Congress exposed a spy, tested loyalties, pushed constitutional boundaries — and launched the career of a man who would leapfrog from the House to the Senate, vice presidency, and presidency and come to define an entire age in American history.

Jim Byron is president and CEO of the Richard Nixon Foundation.