I spent much of the past decade thinking about Herman Mankiewicz, the Hollywood screenwriter who cowrote the original screenplay for Orson Welles’s Citizen Kane and shared its only Oscar. That was the 10 years it took me to research and write a biography of Herman and his younger, more successful brother, Joe (who wrote and directed All About Eve, Cleopatra, and others). During that time, I heard that David Fincher wanted to make a biopic about Herman but was unable to get it produced. Fincher’s father, journalist Jack Fincher, had written a screenplay that centered on Herman’s struggle with Welles over Citizen Kane’s writing credit; Tom Hanks was to play Herman.

Because Jack Fincher died in 2003, I had no idea when—or even if—the project would ever come to fruition. I hoped it would. David Fincher is an extraordinary director, and who better than Hanks to turn irascible Herman into the endearing curmudgeon I imagined him to be. Besides, if millions of people all over the world saw the film, maybe a few thousand would want to know more about Herman and buy my book about the Mankiewicz brothers.

Around 2019, Netflix agreed to film in black-and-white, which had been a nonnegotiable condition of Fincher’s. Gary Oldman replaced Hanks. The script underwent changes. Announcements began appearing. Mank was on its way.

That was when I began to have qualms. Biopics are not documentaries; they are historical fictions that, of necessity, take liberties with the facts. Movies are also infinitely more powerful than the printed page. No matter how many years I spent trying to get my history right, I knew that once the film appeared, Fincher’s Herman would become the accepted version of Herman immediately and for the foreseeable future.

Production started and Netflix began to release photographs from behind the scenes and stills from the film itself. They were elegant, arresting. The trailer, released in October, left me stunned. Its footage included visual scenes and fragments of dialogue so familiar I felt I was time traveling, revisiting events I had experienced many times already. The strength of my emotions startled me. Just the trailer made me choke up.

Then I saw Mank, released earlier this month, in its entirety.

I had already undergone a weird, out-of-body experience the first time I heard the audio version of my book. I listen to my words as I write and rewrite, so I had heard every word of my book countless times. But never had they come from outside my head—and spoken by a man.

The movie took that weirdness to a whole new level. Oldman does not really look like the real Herman, but Tuppence Middleton does resemble his wife Sara, and watching them on-screen as they uttered so many familiar words, I felt as if I was seeing home movies of Herman, Sara, and others I had spent years imagining, like Welles and George S. Kaufman and Louis B. Mayer. Some of the scenes were actual scenes that I, too, had recounted in the book. Sometimes their dialogue was dialogue that I, too, had quoted.

Even when Mank’s narrative deviated from the facts, it rang true. Further upping the weirdness ante, these home movies were not only of an extraordinarily high quality but were eerily familiar. Was I watching a Mankiewicz family version of Citizen Kane?

To Herman’s biographer (me), the short answer was yes, though such a perspective is obviously shared by only a very small segment of the film’s audience (joined, perhaps, by a few Mankiewicz family members). I was pleased with Mank’s Herman and, in truth, relieved. I had seen one of Jack Fincher’s scripts, and his Herman was essentially the same Herman whom I, too, had imagined and hoped I was recreating in my book. But that was just a script, and an old one at that.

There is a familiar lament among writers whose work is adapted to film that what appears on screen has only the most tenuous resemblance to what they wrote. Sometimes all that is left is the title; sometimes not even that. This goes as far back as the beginning of talkies, in the late 1920s. As Herman put it, “When the producer says to you, ‘Now in reel three the fellow shouldn’t kiss the girl, he should kiss the cow,’ ” that fellow was going to kiss the cow, and there wasn’t a thing the writer could do about it.

Joe Mankiewicz became a director for that very reason. After watching directors trample his carefully crafted creations, he decided if you can’t beat ’em, join ’em. Fincher clearly shared his father’s vision, and if Oldman’s noble but flawed Herman is more of a tragic hero than I imagine the real Herman to have been, I don’t begrudge my subject his larger-than-life moment. After all, what are movies for?

Sydney Ladensohn Stern is a freelance writer living in New York City and is the author of The Brothers Mankiewicz: Hope, Heartbreak, and Hollywood Classics (Univ. of Mississippi).