Yes, Die Hard is a Christmas movie. And this scene, featured in my book, 101 Must-See Movie Moments, is one of my favorites.

Writer Rodrick Thorp saw the movie, “The Towering Inferno,” and that night he dreamed of a man being chased through an office building by men with guns. He turned that idea into a sequel to his book, The Detective (made into a movie by that name starring Frank Sinatra). And that book, which he called Nothing Lasts Forever was adapted for one of the most enduringly popular action films of all time, “Die Hard,” starring Bruce Willis.

It is Christmas. New York City cop John McLane (Willis) is on his way to see his estranged wife at her new office in the Nakatomi building, a skyscraper in LA. But the building is taken over by Hans Gruber (Alan Rickman in his first feature film) who wants the authorities to think he is a terrorist. That is a diversion — he is just after money in the form of bearer bonds. Gruber has figured everything out based on standard police procedures. But McLane is anything but standard. He hides out in the building and defeats Gruber’s men one by one as they come after him, despite a lot of interference from well-meaning cops, civilians, and a television reporter and with some help from a good-hearted local police officer.

Willis is ideally cast as a wise-ass cop who does not play by the rules. His wife (Bonnie Bedelia) sees how angry one of the bad guys is and instantly knows her husband is still alive: “Only John can drive someone that crazy.” The script, largely based on Thorp’s book, is clever and exciting. But one of the best plot turns was impromptu, inspired by some off-screen fooling around.

Rickman, now best known as “Harry Potter’s” Severus Snape, was born in London and is a classically trained actor. This is a rare instance where a newcomer playing the villain takes full advantage of the audience’s unfamiliarity to keep surprising us. (Another good example is Edward Norton, who was nominated for an Oscar for his performance in “Primal Fear.”)

As Gruber, Rickman speaks with a German accent. For most of the movie, while we see Gruber, his only contact with McLane is his voice, via the walkie-talkie and intercom system.

Then the two men see each other for the first time and we expect a confrontation. But Rickman was showing off his impeccable American accent between scenes and director John McTiernan realized that this presented a great opportunity for a twist.

McLane rushes in and sees a man who starts talking to him with a perfect American accent and the demeanor of a frightened executive who has never been exposed to violence. Gruber seamlessly eases straight into another accent and another persona. As the final version of the shooting script puts it, “The transformation in his expression and bearing are mind-boggling.” Instead of the icy German barking orders, he is immediately a completely convincing terrified American, begging McLane not to shoot. We know it is Gruber, but McLane doesn’t.

Whether McLane is convinced or not is for us to discover. But at that moment, Rickman is so persuasive, even some audience members may be confused.