Hollywood has operated for decades off this strange, undefinable process, in which millions of creative decisions pass through a single person, for better or for worse. Mank takes an ant’s-eye-view of this system, following Mankiewicz through the corridors of power as he interacts with Welles, the studio moguls Louis B. Mayer and Irving Thalberg, and the media tycoon William Randolph Hearst (Charles Dance). The latter was a friend of Mankiewicz’s who became the chief inspiration for Citizen Kane’s outsize protagonist, Charles Foster Kane. To most of these honchos, Mankiewicz is somewhere between an amusement and an irritant, and for much of Mank’s running time that’s all he is—until he finally decides to fight for his stamp on Kane.