Time travel movies generally try to sidestep the fundamental paradox inherent in being able to go back in time: what if you change things and as a result aren’t born? Yeah, we’ve seen the films where the family portrait slowly fades as one or more children end up unborn (think “Back to the Future”), but still, most sci-fi films try to avoid the problems because they can be really complicated and undermine the sappy love story or whatever else is going on.

Go back and read the original time travel story, Verne’s classic “The Time Machine” and you’ll see how he side-stepped the issue rather neatly. Jules Verne is the exception, however, and most scriptwriters are just stumped by the genre’s challenges.

But just as Nolan’s brilliant film “Inception” took a deep dive into the temporal paradoxes associated with dreams and dreaming, so does the Spierig brothers’ new indie sci-fi film “Predestination” leap headlong into the greatest paradox associated with time travel: meeting your parents. With its quasi-steampunk sensibilities and nimble cuts between the 1940s, 70s and 80s, “Predestination” also has an ambience that’s very reminiscent of yet another brilliant sci-fi film: “Gattica”, perhaps with a bit of “Dark City” mixed in for mood.

“Predestination” revolves around the Temporal Agent known as “The Barkeep” (Ethan Hawke) who has been sent on a complicated set of journeys through the 20th Century to prevent an urban terrorist known as “The Fizzle Bomber” from killing thousands of people. His boss is the shadowy Mr. Robertson (Noah Taylor), who shows up in the most mysterious ways and directs The Barkeep to accomplish various unsavory tasks in different time periods, seemingly without rhyme or reason.

Working as a bartender at a dive bar in the mid-1970’s, The Barkeep first meets John (Sarah Snook), a down on his luck man with an astonishing tale to tell about having been born a woman, training for the Space Corps, having a child, and then having gender reassignment surgery. But John is far more than he seems, as you would expect in a time travel movie that embraces the inherent paradoxes of the genre.

There’s also an alternative futuristic past that the film creates with the Space Corps, a training facility for astronauts (the men) and for what can only be described as astro-escorts, women who are trained to survive the rigors of space while also being taught how to keep the male astronauts happy on multi-year space expeditions. Jane (Snook), who starts her life as an orphaned baby, goes through the program with flying colors, supervised by Robertson, who doesn’t reveal to her his position as head of the Temporal Bureau.

In fact, more than once during the film you’ll gasp “Whaaaaat?” as you realize how things fit together, and by the end of the film, it’s all so neatly stitched together that you’ll immediately want to watch “Predestination” again to better understand all the clues presented earlier in the narrative.

This film also demonstrates of why small budget indie films can be the best place to find thoughtful, interesting stories: the cast delivers uniformly excellent performances, the cinematography is dark and moody, befitting the narrative, and the lack of special effects is a breath of fresh air in a world of $200 million dollar sf/x extravaganzas. It is indeed all about the script, about the story.

Operating with a tight budget and small cast, “Predestination” is a gem of a film that rewards your attention while reveling — and toying — with the paradoxes and complexity of time travel. It’s based on a Robert Heinlein short story called “All You Zombies,” but with much added by Michael and Peter Spierig. And it’s terrific. Go see it. Then again, maybe you already have, in an alternative future where you go back and watch it before you read this review. Or… Um…