A triumph of classical filmmaking for a modern audience, “Adventures of a Mathematician” revisits the Manhattan Project through scientific, ethical and Jewish lenses.

Forgotten your calculus? Simple geometry is more than sufficient to follow the triangular saga of Polish Jewish brainiac Stanislaw Ulam: from the cloistered classrooms of Harvard to Robert Oppenheimer’s atomic-bomb “startup” in dusty New Mexico back to Lvov, Poland (where his parents, sister and niece live in tenuous safety until the Nazis blast across the border).

The 102-minute biographical drama is available for streaming Feb. 26-28 in the S.F.-based Jewish Film Institute’s annual WinterFest, which is virtual this year.

The 2020 movie opens in Cambridge, Massachusetts, on the eve of World War II, where Stan Ulam (Philippe Tlokinski) lives with his younger brother Adam. The news trickling out of Poland, where Ulam was born in 1909, gets objectively worse, but going back to Europe is out of the question.

So Ulam embraces another way of combating the Nazis, proffered by his best friend and fellow emigré scientist Johnny von Neumann (Fabian Kocieki): Join a bunch of other geniuses on the top-secret Manhattan Project.

Writer-director Thor Klein’s intelligent, efficient script relies on our knowledge of the war and the Holocaust (and countless movies on those subjects) to concisely convey the gravity of the situation and, importantly, avoid the familiar cliches. At the same time, Klein skillfully involves us in Ulam’s personal life — he’s a witty man with an appreciation for gambling odds who knows a smart woman when he meets her at a party — without trivializing the larger historical events.

Klein’s other great achievement is making “Adventures of a Mathematician” — which he shot in Germany and Poland with a local crew, European actors, and German, Polish and British financing — totally look and feel like an American film. It’s a masterful trick, which requires dedication and skill at every level of the production.

Klein makes his job easier, admittedly, by depicting Ulam as an acclimated, assimilated American rather than a European fish out of water.

Where “Adventures of a Mathematician,” which takes its title from Ulam’s 1976 memoir, does veer from traditional Hollywood filmmaking is in the dramatic conflict. It’s not the war, which is always off-screen. And tension does enter Ulam’s marriage later in the film (in a relationship we truly care about), but that’s not the movie’s motor, either.

Instead, Klein has made a film about philosophical and existential dilemmas, internalized in the person of Stan Ulam.

Furthermore, Ulam is a cerebral, introverted man who largely keeps his emotions to himself, even when he is debating technical solutions with his equally stubborn boss, Edward Teller (Joel Basman).

Not many Hollywood executives would back a film whose protagonist is pitched on the horns of another triangle, namely the conflicting pulls of intellectual satisfaction, personal morality and professional ambition.

Stanislaw Ulam, action hero, isn’t the easiest sell to American audiences.

But once you get hooked by this utterly accessible film and its remarkable central character, you’re in for a rewarding and thought-provoking experience.

A likable character for much of the film, Ulam becomes more solitary as his doubts grow about devising and building a weapon of mass destruction — especially after the Nazis are defeated. Tlokinski’s performance, which does incorporate a ridiculous (by modern measures) amount of cigarette smoking, is never less than compelling.

“Adventures of a Mathematician” trusts the audience enough to omit most of the melodramatic conversations and passages endemic to a World War II-era film. For example, Ulam’s survivor’s guilt is palpable without the character requiring a speech or a scene to convey it.

One of the highlights of this year’s JFI WinterFest, this film solves for X with nary a misstep.

“Adventures of a Mathematician” is available for streaming Feb. 26-28 in JFI’s WinterFest. $15. 102 minutes. In English and Polish with English subtitles. Rated PG. jfi.org/winterfest-2021