World War II has ended, but instead of emerging victorious, the Americans have lost—and the U.S. has been colonized by Germany and Japan. Robert Childan, a white American citizen of the Japanese-controlled Pacific States of America (PSA), is the owner of a prominent shop that deals in old U.S. memorabilia. He spends his days trying to find just the right objects for his prominent clients: Nobusuke Tagomi, a Japanese trade representative, and Paul and Betty Kasoura, a young couple who are more tolerant of white people than many of their Japanese counterparts. Childan longs to escape the strict racial hierarchy that leaves white people with limited possibilities for housing, work, and socialization.
Tagomi is anxious to sit down with Mr. Baynes, a Swiss plastics expert who has traveled to the PSA for some unclear reason; Tagomi believes Baynes is a spy. To Tagomi’s frustration, Baynes refuses to meet until they are joined by a businessman named Mr. Yatabe. Unfortunately, Chancellor Bormann (the leader of the Nazis) has just died, throwing the world into chaos and delaying Mr. Yatabe’s arrival.
Meanwhile, metalworker Frank Frink is fired from his job at the prominent Wyndham-Matson factory. Frank is Jewish, but he tries to keep this fact a secret. Frank’s colleague Ed McCarthy hopes to start a metal jewelry-making business with Frank. To get seed money for this business, Ed plans to blackmail Wyndham-Matson, since the Wyndham-Matson factory produces fake Civil War guns and sells them off as real antiques, and Ed wants to make this fact public. After consulting the I Ching (an ancient Chinese oracle), Frank agrees, hoping that he will now be able to win his ex-wife Juliana back. Juliana is at present teaching Judo in the Rocky Mountain States, a neutral buffer zone between the Japanese-controlled west coast and the Nazi-controlled east coast.
In disguise, Frank goes to Childan’s shop and informs him that one of his guns—the Colt .44—is a fake. Childan’s faith is deeply shaken, and word of the discovered forgery gets back to Wyndham-Matson; Wyndham-Matson realizes that Frank and Ed have revealed the secret of the fake antiques. Though he gives Frank and Ed the money they want, Wyndham-Matson also vengefully reports to the Nazis that Frank is Jewish.
Still anxious about the fake guns, Childan heads to dinner with the Kasouras—but to his dismay, the young couple disdains his anti-Semitism and anti-Black racism and no friendship blossoms. Meanwhile, Nazi officers Hugo Reiss and Kreuz vom Meere learn that a dissident German spy is currently in the PSA; though the man’s real name is Rudolf Wegener, he is traveling under an alias. Wegener is supposed to meet General Tedeki, a high-ranking Japanese official, but Tedeki is also traveling under an assumed name. J. Goebbels, the Nazi propagandist who has taken temporary control of the party, charges Reiss and vom Meere with stopping Wegener’s meeting at any cost.
Back in the Rocky Mountain States, Juliana has begun an affair with Joe Cinadella, an Italian truck driver with intense Fascist beliefs. Joe is reading a book called The Grasshopper Lies Heavy, which imagines a world in which the U.S. and Britain won World War II. Juliana—like many other characters—is fascinated by the speculative book, banned in Nazi territory. Joe explains that Grasshopper was written by Hawthorne Abendsen, known as “The Man in the High Castle” for all the security he keeps around his home. Abendsen also lives in the Rocky Mountain States, so Joe and Juliana agree to go on a trip: they will drive to Denver and then continue on to Abendsen’s house.
Frank and Ed’s business—Edfrank jewlery—is not nearly as successful as they’d hoped it to be. However, Childan takes a few of their pieces on consignment, and he gradually finds himself moved by the strangely original designs. Childan presents one of the pieces to Paul Kasoura, who suggests that Childan should mass-produce it. Childan is offended by this suggestion, which he feels cheapens the work—he instead commits himself to Edfrank and a contemporary American art movement. Frank, now a known Jew, is arrested; the Nazis want to deport him to the east coast and kill him.
Mr. Yatabe—who is actually General Tedeki—finally arrives in the PSA, and Tagomi schedules his long-awaited meeting with Baynes. In the office, Tagomi learns that Baynes is in fact Rudolf Wegener’s alias. Wegener informs Tedeki that the Nazis are plotting to drop a nuclear bomb on Japan (Operation Dandelion). Wegener believes that the Japanese should align themselves with R. Heydrich, one of the most violent Nazis and another contender to be the next Chancellor, because Heydrich is against Operation Dandelion. Just as Tedeki begins to voice hesitation, several Nazis burst through the door, attempting to kill Wegener. Tagomi, who has always kept a decorative Colt .44. in his desk, shoots and kills the invaders.
Overcome with guilt at having committed murder, Tagomi goes to Childan’s shop in an attempt to return the gun. Childan instead gives Tagomi a triangular piece of Edfrank jewelry. The metal triangle brings Tagomi into an alternative historical timeline (one that resembles what really happened after WWII); he suddenly finds himself in a U.S.-governed San Francisco, where white people treat him with racist disdain (not the other way around). Using the jewelry, Tagomi is able to re-enter his reality. Tagomi is profoundly changed by this experience, as is clear when he refuses to sign extradition papers for Frank. Frank is set free.
Wegener and Tedeki both make it safely home. Wegener reflects on the difficulty of moral action in such an ambiguous world, and he hopes that the Nazis will ultimately destroy each other in their various power struggles. “We can only control the end by making a choice at each step,” Wegener reflects. “We can only hope. And try.”
After a shopping spree in Denver, Juliana realizes that Joe is not an Italian but a Swiss Nazi; his goal is to assassinate Abendsen, and seducing her was merely part of that plan. In a daze, Juliana slits Joe’s throat with a razor. She drives to Abendsen’s house by herself and is shocked to find that it is not a “High Castle” but a regular suburban home. Abendsen explains to Juliana that he did not want to live his life in fear. After she presses, Abendsen also reveals that he used the I Ching to write The Grasshopper Lies Heavy. Juliana insists that The Grasshopper Lies Heavy reveals some kind of fundamental Inner Truth about their world, upsetting Abendsen. Juliana leaves Abendsen’s house and looks with excitement towards the future.
