Somber, sedate, downbeat, thoughtful — all words that apply to the Manhattan Project movie memoir “Adventures of a Mathematician,” a Polish-German co-production filmed in English. Sadly, they sugar-coat how drab and dull this drama about one Polish emigre’s experience of World War II and the moral dilemma he faced when working on “the most gruesome weapon in the universe.”

Philippe Tlokinski (“The Resistance Fighter”) plays Stanislaw Ulam, an accomplished Polish Jew who emigrated to the U.S. in the mid-1930s, and was eventually recruited to the Manhattan Project by his Hungarian physicist John “Johnny” Von Neumann (Fabian Kociecki). That’s where the mathematician was assigned to work with Edward Teller (Joel Basman) and became a key figure in the development of the hydrogen bomb.

Not that they got along while doing it.

“Respect seems to be a word ABSENT from your repertoire!”

Alas for the film, “urgency” seems to be a word absent — in English or German (“dringlichkeit”) — from writer-director Thor Klein’s repertoire.

That little outburst from the notoriously tetchy Teller is almost the only time anyone so much as raises his or her voice in this stunning flat drama. It’s a bloodless enterprise where little is made of the high stakes, the rush to develop the bomb, the loss of family when Russian occupied Poland was invaded by the Germans in June of 1941.

Klein has Ulam call home from his Princeton job to quietly tell his sister he’s deposited money in the bank for them to leave. She calmly agrees. They chat some more, and…

Ulam meets a nice French woman (Esther Garrel) and aspiring writer, Francoise.

“I am from a Jewish family,” she tells him. “There is a lot to write about these days.”

His abrupt “proposal” is pragmatically sound, and every bit as romantic as that seems.

Even the debates among the assorted scientists in Los Alamos have little heat.

“We are scientists, not gods!” I hesitate to add an exclamation point there, as it’s barely played with that level of vehemence,

Ulam loved playing with cards, using them to teach calculus and mentioning “betting against the house” as being the long odds of making a working H-bomb. NOTHING is done with that, no cool card playing demonstrations, zip.

The lead is mild-mannered, showing us a man who internalized everything, from the staggering death toll of the bombs he helped make possible to the birth of his child. The supporting cast is likewise sublimated.

The history is sloppy and the depiction of it lackluster. Ulam skips the July 1945 “Trinity” bomb test, stands outside his apartment and smokes and Klein can’t bother making this look like Los Alamos — at all — or with showing how the bomb lit up the night sky. As he depicts Ulam walking the campus at Princeton one fall day — leaves tumbling everywhere — upon learning that the Germans invaded the other half of Poland, and it actually happened in June, well, “details” aren’t in the guy’s repertoire either.

And the debate over “Why two bombs?” is the sort of gross oversimplification that makes for mediocre drama and dishonest history.

The only consolation in these seriously unadventurous “Adventures” is that Christopher Nolan has announced the Manhattan Project as his next film.

Rating: unrated

Cast: Philippe Tlokinski, Esther Garrel, Fabian Kociecki, Ryan Gage and Joel Basman

Credits: Scripted and directed by Thor Klein. A Samuel Goldwyn release.

Running time: 1:43