Given the history, tragedy and injustice that the New Orleans-filmed “Trumbo” dramatizes, it could have been more effective than it is.

Bryan Cranston portrays Dalton Trumbo, one of Hollywood’s great screenwriters of the 1940s and ’50s. But in the post-World War II U.S., as the Cold War with the Soviet Union reaches a boil, Trumbo’s support of labor unions and civil rights and his membership in the Communist Party are red flags.

A mix of political liberal and unapologetic capitalist, Trumbo draws the witch-hunting gaze of the U.S. House Un-American Activities Committee. He and other members of the Hollywood community are called to a testify in Washington, D.C.

The refusal by Trumbo and others to grovel before the kangaroo court committee ruins their careers. Writers and actors are blacklisted, forbidden to work in the movie industry. Trumbo, the once well-to-do screenwriter star, even serves prison time for contempt of congress.

Cranston, despite some distracting versions of Trumbo’s mustache, presents the writer’s elegance and wit with nicely turned grace. But the movie Cranston is in concerns itself more with the mechanics and cosmetics of the story than the deeper aspects of the writer, his work and the blacklist. The would-be heartbreaking details of Trumbo’s and his peers’ interrupted lives unreels in uninspiring, obligatory set pieces.

The movie’s tone also veers from drama that’s not heavy enough to full-on comedy. And it’s not good for an otherwise serious biopic when a supporting comic character is more interesting than the story’s beleaguered protagonist.

Maybe that’s because the act of writing — normally a solitary, stationary pursuit — isn’t photogenic. That also goes for Trumbo’s habit of pecking out scripts on a manual typewriter in his bathtub as he smokes and takes Benzedrine.

John Goodman co-stars as the supporting character who most of all enlivens “Trumbo.” After Trumbo and others are blacklisted, they use pseudonyms to write for Goodman’s Frank King, a producer whose B-movie factory makes cheap gangster, horror and sci-fi flicks. When the studio invests in a gorilla suit, for instance, it must find a script with a gorilla in it.

Goodman animates his outsized performance as King with a red-blooded authenticity the other supporting characters in “Trumbo” lack. His performance is so funny it probably belongs somewhere other than “Trumbo.”

Also in the supporting cast, Helen Mirren plays anti-Communist gossip columnist and Trumbo nemesis Hedda Hopper. John Wayne and money-driven Hollywood studio heads who bow to the political pressure are in the anti-Trumbo corner, too.

Like “Trumbo” in general, shallowness at the screenplay level mars Mirren’s Hopper, David James Elliott’s John Wayne, Michael Stuhlbarg’s Edward G. Robinson and Dean O’Gorman’s Kirk Douglas. The latter two performances, especially, are self-conscious approximations of the real-life Douglas and Robinson.

Despite Cranston’s commendable work and Goodman’s funny business, the underwhelming “Trumbo” leaves a door open for someone, sometime to make a better movie about a great screenwriter who lived long enough to be vindicated and honored.