There's just the briefest of alternate histories in Parallels - and old newspaper, brought to our world from a parallel reality, with the headline that Clinton was assassinated and Gore sworn in. Otherwise, our three main characters - a brother and sister in their 20s, and a neighbor, the same age, who loves the sister - visit just two alternate worlds.
One is a post nuclear-holocaust world - or, at least, a city - with the trappings of a post-apocalyptic Mad Max ragged skeleton of civilization. Far more interesting and better realized is an alternate Earth which is a few decades further into the future than ours as far as technological development - meaning, it's the exact same date in all Earths, but some are more advanced than others. This high-tech Earth has nice digital screens. differently named fast food, and literally digital palm or finger recognition devices.
Some of what is going on, including that our threesome didn't time travel to the more advanced Earth, is explained to us by a fourth character, Polly, apparently the same age as our three travelers. She, for some reason not explained, and revealed only at the end, exists in triplicate or more in the building. One of her serves as a tour guide to some extent in each alternate world that our trio enters. She likely has some connection to the people or beings who constructed the building and its alternate reality portals.
I think the story has potential, and I'd like to see it realized on the screen in our reality. Its deliberate avoidance of time travel, as well as weighty alternate history such as The Man in High Castle, gives it a tough row to hoe - a tough road to hoe, too, in an alternate reality in which "road" not "roe" was the expression - but that also makes this narrative original, welcome, and even refreshing.
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