Film buffs salivating over the prospect of David Fincher taking on the making of “Citizen Kane” may be left a tad dry-mouthed by “Mank,” his Netflix bio-pic of “Kane” co-writer Herman J. Mankiewicz.

Filmed in digital video black and white, it’s a mostly sizzle-free blend of fact and fiction based on Fincher’s late father Jack Fincher’s screenplay. “Mank” is a fair-enough revisit of the writing credit battle over that “Kane” screenplay, a fine buffing of the image of actress and William Randolph Heart mistress Marion Davies and another acting showcase for the great Gary Oldman.

Oldman — who is terrific in the part — had his own battles with substance abuse — like the wit/screenwriter he portrays in the title role. He’s a high-mileage 62, playing a higher-mileage 43 year-old. Pairing him up with Tom Pelphrey as brother Joseph Mankiewicz and Tuppence Middleton as Mank’s long-suffering wife, “Poor Sara” Mankiewicz, both actors half Oldman’s age, makes that gap obvious and worth wincing over.

But Amanda Seyfried is Brooklyn streetwise and warm Davies, a reinvention not unlike what Tarantino did for Sharon Tate with “Once Upon a Time…in Hollywood.” And Charles Dance brings the upper class menace to newspaper baron and “Citizen Kane” villain Hearst.

“Mank” is built on two timelines — the writing of the first draft of “Kane” in a remote ranch in Victorville, California, where Welles’ producer and confidante John Houseman (Sam Troughton) drops the easily-distracted alcoholic Mank off with a German nurse (Monika Gossmann) and an English typist (Lily Collins). His orders? Write the first draft of “American,” the working title that would become “Citizen Kane.”

Houseman is worried sick about losing his job for not getting this piece of work done.

“I’ve never BEEN fired.” To which Mank quips, “I’ve never NOT been fired.”

The second timeline is Mank’s Hollywood history, a former New York newspaper drama critic who came to California and struck it rich as a screenwriter and uncredited “script doctor.” Well, he would have struck it rich if he hadn’t gambled and drank away his paychecks and pissed off everybody he ever worked for.

We too-briefly see his place within the mob of New York journalists he helped lure to town at the end of the silent film era — S.J. Perelman, Charles MacArthur, George S. Kaufman and Ben Hecht.

And we see him run afoul of studio chiefs, most famously Louis B. Mayer of MGM. Arliss Howard is a fine actor who suggests too little of the monstrous, bullying weeper Mayer, although he manages a fine tirade or two.

The Jack Fincher script’s conceit follows the Hollywood lore that Mank’s social mixing with Hearst, Davies and Mayer inspired his take-down of Hearst et al with “Kane.” Mank’s sharp tongue — loosened when he drank, which was always, led to cutting wisecracks. He insulted one bigshot too many too often and was banished, so the legend goes. He took what he knew about the Hearst story and circle and scandalized it into a movie.

He even named the sled after Hearst’s nickname for his girlfriend’s genitals. As Marian was fond of saying then and says often in the film, “Aw, Nertz!”

The story wanders far from facts as it pinpoints political differences as the source of this friction, making the Hollywood division over the 1934 California gubernatorial race — with union guys like the nascent Writer’s Guild pulling for socialist author Upton Sinclair in his battle with the Republican establishment candidate, backed by the Big Studios.

And the film compresses the efforts to suppress “Citizen Kane” into furtive and fervid calls and visits to Victorville. Mayer, his pal and sometime backer Hearst and others fretted over Mank and Welles “hunting dangerous game” in sending up Hearst. There’s even the suggestion of remorse as Davies sweetly confronts the writer in a scene that never happened.

Yes, Welles first used Mankiewicz for radio scripts, and tried to take sole credit for the Kane screenplay. But decades of exhaustive research have demonstrated his contribution to the rewriting was substantial, and that his direction was paramount to the film’s reputation. Robert Carringer’s “The Making of Citizen Kane” settled that argument 40 years ago.

Fincher creates a detailed if somewhat visually washed-out milieu of smokey executive suites, baroque Hearst Castle (San Simeon) parties and nightclubs contrasted with the “dry” austerity of Mank’s desert writing retreat.

Oldman is compelling, first scene to last. Yes, the man can play a convincing wit and convincing drunk. I wanted more twinkle from him, but the decision was made to play this Mank as a cynic and alcoholic burnout. Even his younger scenes lack the “court jester” personality to match the zingers.

At least Seyfried and Dance sparkle in support.

The passing parade of witty writers and Hollywood legends is given seriously short shrift, with lightweight casting to match. The players, by and large, aren’t up to making a cutting impression playing larger-than-life figures in tiny character actor roles. A decent Houseman impression here, a hint of Norma Shearer there — that’s about it.

The uptempo jazz that dominates the score cannot disguise the film’s stolid pacing.

And “Mank’s” abrupt finale, at the end of a meandering story of writing and remembering (Welles, played by Tom Burke, is barely in this), leaves something to be desired as well.

The funny lines are here. But where’s the fun, the breathless/childish conspiracy it took to make the movie, the boyishness Mankiewicz claimed Welles (who was just 24) brought out in him writing “Kane,” which Mank enthusiastically realized would be the defining work of his career?

Fincher’s made a sometimes fascinating/sometimes plodding recreation of film history, perhaps with its own share of Oscar bait attached. But his richly-detailed movie just reminds us that the more modest “RKO 281,” about the actual filming of “Kane,” and “The Cradle Will Rock” and “Me and Orson Welles,” about Welles’ days shaking up New York theater, were a lot more entertaining.

MPA Rating: R for some language

Cast: Gary Oldman, Amanda Seyfried, Lily Collins,
Tom Pelphrey, Tuppence Middleton, Tom Burke, Arliss Howard and Charles Dance

Credits: Directed by David Fincher, script by Jack Fincher. A Netflix release.

Running time: 2:13