As Henry Lehman says, and repeatedly, “Baruch Hashem.”

He says it with gratitude for having made it across the Atlantic. I’m saying it with thanks, too, but for seeing a play which, though it highlights the Jewishness of the firm behind the biggest financial crisis since the Wall Street Crash, does it without leaving a whiff of Jewish conspiracy hanging in the air.

Stefano Massini’s hit European epic, adapted in three parts with two intervals for the National by Ben Power, begins at the end. That is to say, the play opens in 2008 with the bankruptcy of one of the biggest banking corporations in America.

Like an old black-and-white film — in nearly every aspect of its design this production is in monochrome — it then spools back to where it all began, to 1844, when the Bavarian-born Hyam Lehman, played by Simon Russell Beale, disembarked from the ship that carried him from Germany to Ellis Island, where the immigration official can’t pronounce his forename, so calls him Henry. Classic.

After setting up shop in Montgomery, Alabama, where slavery is still going strong, Henry is joined by his brothers, the aggressive Emanuel (Ben Miles) and the diplomatic Mayer (Adam Godley). And it is through these three that Sam Mendes’s production establishes its distinctive form of storytelling. Speaking in the third person about themselves and each other, the brothers describe the events via direct address to the audience — a kind of recital — as if their words were set down for mankind to live by and learn from. Like the Talmud.

Over the following three-and-a-half hours or more, the plot never rests. The brothers move from selling clothes in their shop, to selling cotton to companies, and then coffee to, well, whoever it is who buys coffee by the ton. Would that be commodity dealers? It doesn’t much matter. Thankfully, the play doesn’t get hung up on the financial systems the Lehman Brothers help invent and which eventually failed. It’s more interested in exploring who these people are, or were. That said, there is no overbearing anti-capitalism message to take home. However, there is, deep within, a morality tale.

Mendes’s production is as slick as a glass skyscraper. Indeed, the action is performed by the three leads within one of the Lehman Bros Manhattan glass offices and in front of an IMAX-style screen on which is projected dizzying displays of the play’s locations; low cotton fields in Alabama, the high spires of Manhattan when it moves to New York. Yet, away from the advanced stagecraft, the essence of this show lies in the acting.

Beale, Miles, Godley not only play the first generation of Lehmans, but the generations that followed, the wives they married, the children they begat, the factory owners they struck deals with. All three are superb, but it’s Beale who is in complete command of every comedic nuance, whether as a coy suitor to Henry’s austere son Philip or a rabbi shooting fearful glances at the disruptive Emanuel’s son Herman. “In my opinion, Hashem, instead of wasting time with plagues, should have simply killed the pharaoh” declares the nine-year-old.

And this develops as a kind of subliminal sup-plot. As the corporation moves away from being the kind of bank that finances the making of things, and towards the kind of business that finances the making of money, so each generation becomes less Jewish than the previous one.

The humanity of Beale’s Henry is superseded by Philip’s more intellectual qualities.

Meanwhile, the mild-mannered Mayer’s son Bobby is equally precocious in his own way. “But in his veins is not even a distant memory of Bavaria or Alabama”.

You come away none the wiser about why it was that one of America’s biggest banks failed. But it goes a long way to explaining how the family succeeded.

And much of that, the play suggests, was to do with the outsider Jewishness of the first Lehmans to land in America, and an ability to see opportunities that lay between established conventions and rules.