"You ever think," Juliana Crain wonders, "how different life would be if you could change just one thing?"

It's almost as if she knows she's one of the main characters in a story set in just such an alternate timeline: Amazon's new drama "The Man in the High Castle," where the Axis powers won World War II and divided America up into separate Japanese and German-run states.

Adapted from Philip K. Dick's novel by producer Frank Spotnitz ("The X-Files," "Hunted"), the series (it debuts Friday; I've seen the first six episodes) doesn't get much into the backstory of how the Allies lost the war — all we know is that the Nazis dropped an atomic bomb on Washington, D.C. — but simply deposits us in a version of 1962 New York where swastikas adorn every corner of Times Square, Hitler's a beloved leader who appears frequently on television, and non-white faces have all but vanished without comment.

It's an impressive piece of visual world-building, since the show has to first conjure up the early "Mad Men" era, then imagine all the ways it would look and feel differently under German or Japanese rule, from technology to popular culture. (Instead of "Dragnet," "American Reich" is the popular just-the-facts cop show of the day.) The palette is all cool greys and blues, and digital effects have become convincing (and, for TV purposes, fast and cheap) enough that the series can present these altered versions of New York and San Francisco without seeming like it's showing off. This is just what this world is supposed to look like.

Or is it? Through a pair of separate but intertwining plots involving Juliana (Alexa Davalos), an aikido student in San Francisco, and Joe Blake (Luke Kleintank), a new member of the American resistance in New York, we learn of the title character. Depending on whom you ask, he either makes or collects films that depict a reality that seems alien to Juliana and Joe, but looks perfectly natural to us, where the Allies won the war.

Are these films imaginative works of fiction? Or does the Man in the High Castle somehow know that this world is wrong, and perhaps have a way to fix it?

That's not made clear in the series' early episodes, which deal with a collection of overlapping schemes by the resistance, the Nazis, and/or the Japanese, and which are watchable more for the look and feel of this altered world than for the stories or characters. The pacing is wobbly, and while the actors all seem period-appropriate (Davalos, whose previous series was TNT's '40s crime drama "Mob City," is a graceful acting time traveler), the only character who really comes to life as more than a functionary of the plot is one of Spotnitz's creations: Obergruppenführer John Smith (Rufus Sewell), an American who's grown a little too comfortable in his Gestapo uniform. From our perspective, he's the chief villain of the piece, but Sewell plays him not as a mustache-twirling monster, but an all-American boy supremely loyal to the current law of the land. While  also necessarily for the story to keep moving forward, he's the only character who invites curiosity about his inner life or backstory.

Still, the world itself is fascinating and fully-realized enough to compensate for the people who live there. A show set in the actual 1962 featuring these characters would probably be a drag, but drop a few Nazi flags in places where they have no business being, and things become much more interesting, even if they're not the least bit right.

Alan Sepinwall may be reached at sepinwall@hitfix.com

Alan Sepinwall has been reviewing television since the mid-'90s, first for Tony Soprano's hometown paper, The Star-Ledger, and now for HitFix. His new book, "TV (The Book)" about the 100 greatest shows of all time, is available now. He can be reached at sepinwall@hitfix.com