I spoke with Mark via telephone in September as he was wrapping up production of "Harry Potter and the Sorcerer’s Stone" in London. The film is set to open November 16, 2001. I asked him what he thought some of the challenges were in bringing J.K. Rowling's enormously popular Harry Potter book to life.

"Well, it’s loaded with special effects. We worked with as many as eight different companies. Trying to bring a Quidditch game to life and a three headed dog…you can imagine. We also filmed all over England so that was a challenge."

The movie’s characters include goblins, a troll, ghosts, owls, a life size chess set, and the evil Lord Voldemort. And where there are witches and wizards there must be flying brooms, in Harry’s case, it’s a Nimbus 2000.

I asked Mark if he had heard that some "real" witches were concerned Harry was flying his Nimbus 2000 incorrectly.

"Yes, I have heard that," he said, "They say the brush part of the broom should be in front. That seems backwards to me. We decided not to change it."

In keeping with the book, the cast is all English. Eleven-year-old Daniel Radcliffe plays the orphan Harry Potter, the boy with the lightening bolt scar on his forehead. He is forced to live "in the cupboard under the stairs" by his dreadful relatives, the Dursleys until the day a magical letter arrives.

Daniel began his acting career by playing another orphan, David Copperfield. He is joined by Rupert Grint as Harry’s loyal friend, Ron Weasley, and Emma Watson as the brainy, Hermione Granger. Albus Dumbledore, the headmaster of the wizarding school called Hogwarts, is played by Richard Harris. Allen Rickman plays the slippery Severus Snape and Maggie Smith is Professor McGonagall. Robbie Coltrane is the gentle giant, Hagrid, and who else but John Cleese could play the ghost, Nearly Headless Nick?

"The cast was really terrific and Chris Columbus is a phenomenal director. He always believed it was essential to stay close to the book." says Mark.

The four Harry Potter books written so far, were penned by a young, single Scottish mom, J.K. (Joanne Kathleen) Rowling. The legend of the author as a penniless mom on the dole is one she shuns. But of late, she’s made some sizeable donations to The Council for One Parent Families. And she has offered proceeds from sales of two companion books to a project that fights famine in Africa. The books are titled after a couple of Harry’s textbooks. They are "Quidditch Through the Ages" and "Fantastic Beasts and Where to Find Them".

Her Harry Potter books have sold more than 100 million copies worldwide and have been translated into 42 different languages, including Zulu and Albanian. They are so popular with kids (and adults) that they were responsible for restructuring the New York Times bestseller list. In June of 2000 shortly before the release of the fourth book, the New York Times announced a separate Children’s Best Seller List because Harry Potter was knocking adult best sellers off the list. Now, that’s magic. Warner brothers is betting the movie will do as well.

"We didn’t want to change the book, says Mark. "We saw our function as that of illustrators. If we are able to bring the visuals from Rowling's book to life then we’ve done our job."

In an interview with the Arizona Republic in November 2000, Rowling said, "I’ve been astonished at how much (creative) input I’ve been allowed. They ask me questions. They check things. They’ve been very collaborative. None of us is going to see (on screen) the Hogwarts we see inside our head…but it’s very close."

Mark says Rowling didn’t visit the set often but that she was a constant advisor. "She’s been terrific. If we have questions about details she’s very willing to help. She knows her world and her characters so well. "

When he isn’t re-creating magical worlds, Mark unwinds at home. I asked him how often his work schedule allowed him to come back to Tulsa.

"I try to make it back about every two weeks. Lately, we’ve been really busy finishing the first Harry Potter. We’re working on the John Williams score right now and approving the visual effects. We are also prepping for second film."

The second film, "Harry Potter and the Chamber of Secrets" is expected to come out next November, about the same time as Rowling releases her 5^th book, "Harry Potter and the Order of the Phoenix". She has plans for a total of seven books. The film rights to "Harry Potter and the Prisoner of Azkaban" and "Harry Potter and the Goblet of Fire" have been purchased by Warner Brothers, but Mark said it was too soon to know whether his company would be involved in those.