Iron Man and Captain America may dominate the domestic box office, but for the story of a real patriotic hero, look no further than The Spy Behind Home Plate, director Aviva Kempner’s fleet, comprehensive and altogether inspiring documentary about Morris “Moe” Berg.

The son of Ukrainian-Jewish immigrants who grew up in Newark, New Jersey, Berg was a talented student and an equally accomplished baseball player, eventually reaching the majors. He also attended Princeton (where he graduated magna cum laude) and Columbia (where he got his law degree); learned to speak 10 languages fluently; and established himself as a ladies’ man and intellectual radio sensation.

And that was all before he became a honest-to-goodness WWII American espionage agent.

It’s hard to imagine a better resume, or life, than the one fashioned by Berg, whose exploits—previously dramatized by last year’s dull Paul Rudd-led The Catcher Was a Spy—are thoroughly detailed by this gripping non-fiction effort. Kempner’s doc is constructed from a treasure trove of archival photos and film footage of Berg on the field, at home, and working overseas; archival movie and newsreel clips that capture the atmosphere of the era; and abundant interviews (both old and new) with family, friends, colleagues, fellow servicemen, journalists and historians that serve as its de facto narration. The Spy Behind Home Plate is assembled with the same deftness that Kempner brought to her prior The Life and Times of Hank Greenberg. Moreover, like that earlier portrait of a larger-than-life Jewish ballplayer, it has a keen sense of the micro and macro forces at play in its tale.

It was apparent from an early age that Berg was possessed of a formidable intellect, which is why when he chose to pursue his big-league dreams, his father Bernard—who ran a pharmacy, and had legal aspirations for his son—objected, albeit to no avail. Despite his career-long inability to hit, Berg became a slick-fielding shortstop and, by chance, a better-fielding catcher for the Chicago White Sox, Cleveland Indians and Boston Red Sox. By all accounts, he was a gregarious and supportive teammate beloved by all (including rookies who benefited from his counsel and encouragement), and he’d ultimately transition into coaching for two seasons (1940-1941) with Boston.

Berg’s athletic prowess, however, was all the more impressive for being the least impressive thing about him. A voracious reader, he was known to pore over countless daily newspapers, and was so protective about them that if anyone touched one, he’d refuse to read it. He was an astute writer as well, penning in the September 1941 issue of The Atlantic an article entitled “Pitchers and Catchers” that laid out the symbiotic relationship between the two positions. Including references to Montaigne and Socrates, and analogizing the catcher as the diamond’s figurative Cerberus (aka “The Hound of Hades”), it remains a highly acclaimed sports piece, having been republished in numerous anthologies.

This alone would make Berg an amazing, unique and admirable figure. Yet as conveyed by The Spy Behind Home Plate, what also distinguished him was his love of travel, foreign cultures, geopolitics, and his native country. Those would all contribute to his future career as a spy, which seems to have begun, covertly, during two trips to Japan: first in 1932 as part of a group of MLB players organized to teach baseball seminars at the country’s universities; and then in 1934 as a member of an all-star coalition that included Babe Ruth and Lou Gehrig. On that second trip, Berg snuck away and, disguised as a Japanese man, visited Tokyo’s Saint Luke’s Hospital (the city’s tallest building), where he pretended to visit an ambassador’s pregnant daughter and, in reality, made his way up to the roof to film a 360-degree view of the skyline. That material would subsequently be used for strategic air raids by U.S. forces.

To call Berg “a renaissance man,” as one talking head does, is almost to sell him short. In the aftermath of the attack on Pearl Harbor, Berg—highly educated, worldly, multilingual, daring, and having followed up his Japan trip with a stop in Germany, where the Nazi Party was preparing for war—proved an ideal candidate for President Roosevelt’s newly formed Office of Strategic Services (OSS), the precursor to the CIA. And considering his baseball celebrity, which was furthered by multiple appearances on the hit radio quiz show Information Please, he had the perfect cover for his clandestine overseas missions.

“If he wasn’t real, you’d have to invent him,” says OSS Society President Charles Pinck in The Spy Behind Home Plate, which even brings into its tale Ian Fleming, whose iconic 007 boasts quite a few of Berg’s own characteristics. Throughout WWII, Berg operated as a spy, and in its thrilling final passages, Kempner’s film details his efforts to track down intel about Hitler’s nuclear bomb plans (and progress). That culminated in a trip to Zurich where Berg, with a cyanide capsule in one pocket and a gun in the other, posed as a Swiss student in order to attend a speech by famed German physicist Werner Heisenberg—whom he was to kill, if he found out that the Germans were nearing completion on such a weapon. “It had to be about as dangerous a job as a fellow could undertake,” remarks OSS Agent Earl Brodie regarding that assignment, and it resulted in a private conversation between Berg and Heisenberg that informed the U.S. that their own Manhattan Project wouldn’t be surpassed by the Nazis.

The fact that Berg accomplished all this and more during WWII—a later extraction of an Italian scientist would reportedly compel FDR to exclaim, “I see that Moe is still catching very well!”—is additionally astounding given his Jewish heritage. As many recount, Berg was fiercely dedicated to his homeland, and Kempner’s film emphasizes that he sought to protect it without any interest in accolades—a textual coda reveals that he even turned down the Medal of Freedom offered to him by President Truman in 1946.

Such humility befits a man who genuinely earned the moniker “hero.” It’s a designation he would have balked at, but which fit him like a glove.