If you’ve heard that “Mank” is about the making of Orson Welles’ 1941 masterpiece, “Citizen Kane,” you’ve been misled. In fact, there’s very little about that movie in this one, despite the framing device of Herman Mankiewicz laid up in bed with a broken leg while he works on the “Kane” screenplay (which won an Oscar).

There’s not much drama in watching someone write (or, in Mankiewicz’s case, dictate the script to his assistant/typist, Rita Alexander). Instead, in flashback, we learn more about Mankiewicz’s volatile history, replete with alcoholism and bouts of rage, particularly at Louis B. Mayer and Irving Thalberg, the movie studio executives he worked for. Because of his way with words, Mank was apparently a beloved dinner guest of William Randolph Hearst and close friend of Hearst’s girlfriend, the actress Marion Davies. It was his access to them that laid the groundwork for the development of Welles’ movie about a fictional version of the mega-rich, powerful newspaper publisher.

But “Mank” also takes long digressions into the 1934 California gubernatorial election, in which socialist author Upton Sinclair ran as the Democratic candidate, who was defeated by the incumbent governor, Frank Merriam. Mayer, Thalberg, Hearst, and other characters in the movie were ostensibly involved in spreading propaganda against Sinclair, and Mankiewicz was drawn into the matter, but it’s unclear from “Mank” whether their efforts had any effect on the outcome. Rather, the whole race is portrayed as yet another instance of rich white men smearing the candidate they didn’t like through innuendo and false claims. How far we’ve come, right?

As for the cast, Gary Oldman chews every bit of scenery he encounters as Mankiewicz, showing off his ability to play drunk in nearly every scene. Amanda Seyfried is fine as Davies, although she’s only given one scene in which she’s more than mere window dressing. Tom Burke captures the voice and attitude of Welles — who only appears in three or four scenes, mostly on the phone — while Sam Troughton portrays John Houseman as nothing more than an errand boy for the wunderkind director. The rest of the cast, including the actors who play the movie moguls, seem to exist merely as characters for Mankiewicz to run roughshod over in extended speeches full of fury and supposed wit.

Director David Fincher, working from a script by his father, switches between eras so often it’s hard to keep track of what’s going on and where things stand in the various relationships of his characters. The greater problem is that “Mank” offers no one likable enough to root for, while bathing the entire venture in a deep layer of pretension. If you’re not familiar with the many famous names sprinkled throughout the script, you won’t learn much about them and, in the end, you may find yourself wondering — as I did — how much more entertaining a movie about the actual making of “Citizen Kane” might be.

I give “Mank” a 3 out of 10. It is now streaming on Netflix.