Harry Potter actor Alfred Enoch on playing Mark Rothko's assistant in Red
Two actors. Two characters. One stage. One interval-free show. Copious amounts of red paint.
Those are the basic ingredients that make up Red - a play about American artist Mark Rothko - which has just opened in the West End, nearly a decade on from stints at London's Donmar and on Broadway.
Alfred Molina reprises his role as Rothko in the new production - but, instead of acting opposite Eddie Redmayne as he did in 2009, there's a new face on stage this time.
The role of Ken - Rothko's young assistant - has been taken by Alfred Enoch, who is perhaps best known as Dean Thomas in seven of the eight Harry Potter films.
"Fifty per cent of the cast has changed since the first production," laughs director Michael Grandage. "And we're also doing it now on a large West End stage as opposed to an intimate studio theatre.
"It seems to be a play which speaks to the idea of mentors and mentees, teachers and pupils, fathers and sons.
"And it seems to be saying something that I've long believed in, but nobody ever talks about much, which is that the young person can give the older person in that relationship as much information as the [older person can to the young].
"I think when we talk about a mentor, we assume everything goes in one direction, and this play rather brilliantly investigates the idea that when two people are in a room, one young and one old, both learn from each other."
From the marketing and description of the show, it would be easy to assume Red is just a high-brow play about some nice paintings.
But it has complexity at its core. Set over the course of two years in the late 1950s, the play sees the relationship and dynamic between the two characters develop and change a great deal.
The Sorkin-esque quickfire dialogue is perhaps one of the most notable things about John Logan's script.
"For me, it's not so much the amount of dialogue, it's the speed of thought of the characters," says Enoch.
"They think fast and they talk fast, and they can turn ideas on a sixpence. So it's a challenge just maintaining that mental energy, that nimbleness."
Added to which, there's a great deal of physical movement for a play entirely set in Rothko's studio.
"That's one of the exciting things about this play, that as much as it's this thrilling exchange between two bright people, it also shows you what it is physically to be an artist, to be in the studio, mixing paint, stretching the canvas, making a frame, all that happens on stage," Enoch says.
The actor says it was tricky to master the craft of being an artist - while having intense conversations at the same time. "There's a lot of stuff!" he says.
"So it was quite a lot to get the hang of because you're doing these two things at the same time, because that's what these characters are capable of, they're fluent in both of them."
Molina, who has starred in Chocolat, An Education and Feud: Bette and Joan, says his main reason for returning was "getting to work with a fantastic actor, in a beautiful theatre, and doing it in the West End - which was really a bit of unfinished business".
The actor says the relationship at the core of the play was what originally attracted him to the show.
"These are very bright men who can talk and think very quickly, and they're not afraid of their thoughts. They don't think twice because they don't have to think twice," he says.
"They're so sure about what they believe and how they perceive things, and that's why there's this wonderful tension between them.
"It starts off with Rothko being a bit of a bully, telling Ken this is the way things are, and then of course the relationship changes and Ken starts to evolve and become his own person, and he then can challenge Rothko on his own terms."
Ann Treneman awarded the new production five stars in her review for The Times.
"Michael Grandage directs and, at 90 minutes straight through, he builds up the layers, not unlike the paint on a Rothko canvas, until you care deeply about both men," she wrote.
"The connection only gets more powerful. The themes of student and teacher, father and son pulsate along with those paintings on stage. What do we see? Red, of course, but in the best possible way."
The Telegraph said: "Just as we're encouraged to realise there's no such thing as a basic wash of colour - everything requires contemplation - so there's no such thing as a simple debate about art.
"The evening - only 90 minutes - serves as a fascinating biographical footnote but pivots into something more profound and probing."
The Stage's Natasha Tripney was more lukewarm in her three-star review, writing: "The immense convenience of Ken's murdered parents as a plot point, the red of their blood staining his memory, feels even more contrived on second viewing."
But she praised Enoch, saying: "He brings a completely different energy to the production.
"He's a warmer presence than Redmayne was and he reframes some of the play's discussion about, say, the symbolism of blackness in art. He invigorates the play, while also making its limitations apparent."
Red is at the Wyndham's Theatre in London until 28 July.