To save the future he must reshape the past
Why it is hard sci-fi
A film built around a single closed timelike curve that is also a working causal loop. The Bartender is a temporal agent recruiting his own past selves for a mission that loops back to the formation of the agency itself. The film commits to a hard rule. The loop is consistent. There is no free variable. Everyone in the film is a single person at different points in the loop.
Science inside it
Closed timelike curves, ontological paradox by design, intersex biology as a plot mechanism. The film leans on the Heinlein story All You Zombies and treats the loop as a self-consistent solution rather than a contradiction. That is one of the two coherent ways to handle a time machine, and the film picks one and is faithful to it.
Spoiler alert
The Bartender, the Unmarried Mother, and the Fizzle Bomber are all the same person at three points in their life, born from a sex change after giving birth to themselves. The agency that recruited them has always been one person, recursively. The film treats this not as a twist to be solved but as a working solution to the equations.