For an artist whose huge, abstract canvases inspire the kind of silent awe evoked when walking to the edge of the Grand Canyon, say, or when taking in the sweep of the Milky Way on a clear, moonless night, Mark Rothko is a bit of a loud-mouth. But then, as his character says in John Logan’s play, he is one of the Russian-born “talky, thinky Jews” who emerged from the ghetto.

Talking and thinking come as naturally to him as painting. So, apparently, do bullying, bellowing and brooding.

Set in Rothko’s New York studio in 1958, the play was first seen in 2009 with Alfred Molina playing Rothko and Eddie Redmayne as his fictional assistant, Ken. This revival sees Molina —shaven-headed and temperament set either to a notch below explosive or to full-blown eruption — reprise that performance. Only this time, instead of playing opposite Redmayne, Molina is accompanied on stage in this two-hander by former Harry Potter regular Alfred Enoch whose grown-up projects these days include Troy and How To Get Away With Murder.

Over the play’s uninterrupted 90 minutes, Enoch grows into the role much as Ken’s diffidence matures into self-confidence. The assistant’s first day at work is a baptism of fire. Rothko barks art-related questions at him about what he sees when he looks at a painting and how much he has read.

“You cannot be an artist unless you are civilised,” Rothko declares to this neophyte, though it’s delivered less like advice than a punch in the stomach.

Ken arrives in the job as Rothko is working on a series of red murals. Under the right lighting conditions — supplied here by Neil Austin — these abstract works are alive with a kind of primeval pulse. Forgive the indulgence of a theatre review attempting a spot of art criticism, but when I saw these paintings at the Tate Modern a few years ago it was like viewing the moment of galactic creation, that is the point at which a universe of nothing becomes a universe full of something.

“They’re for a restaurant,” he explains to Ken. It’s the best line in the play. Rothko’s ambition is to turn the eatery into a kind of temple. But with gathering self-loathing he realises he has sold out.

Molina delivers a superb portrait of a monumental ego. And not since Yasmina Reza’s massive hit Art, has art evoked such eloquent exchanges about its function and value.

But a two-hander needs two well-drawn characters. And, in coming to the play a second time, it feels as though the character of Ken is more a simple sketch than a proper portrait. The lad has a tragic history we learn. His parents were murdered during a burglary when he was seven, which ,for just one fleeting moment, is enough to make Molina’s artist stop thinking about himself.

Yet Ken’s history feels as though Logan has reached for an off-the-shelf tragedy with which to give the character some dramatic heft.

And have I missed something about the answer Ken gives to Rothko’s rhetorical question about selling his painting to philistines? “How will they forgive me” Rothko asks of his works as if they were his children.

“They are just paintings,” says Ken, which is both true and yet an oddly crass thing for an aspiring artist to say.

Still, some of the exchanges about art are thrillingly and passionately articulate. When Ken confronts his employer over his misplaced vanity, Michael Grandage’s production crackles with tension.

Yet there is nothing here as dramatic as the art itself. Copies they may be, but Rothko’s great canvases hang in mute eternal judgment of the flawed people in the company. They, at least, are no less potent than they were when the play was seen first time round.