As a prolific reviewer, you tend to often discuss a film in terms of traditional arcs, and riffs off those same arcs.
Which is why it is always a treat when a film comes along that throws the script template out the window and forges its own path.
This is such a film. It reminded me of THE INCREDIBLE SHRINKING MAN 1957, the first legitimate A-list sci-fi that, like this film, started off in what seemed a traditional manner -- and then went down a plot superhiway that no one had ever seen before.
It is not a perfect film. It has some flaws. For example, the first 30 minutes are better (more impact, more empathy, more entertaining) than the last 60 minutes. Which is not to suggest that the last hour is bad, merely that the first half-hour is drop-dead stunning and unforgettable.
And the director often seems confused about who the real star is? Ditto for the PR dept of the studio. If you check the IMDb reference, you will see that the young girl so brilliantly played by Sennia Nanua is given billing lower down on the cast list. That's an error. Sennia IS the film -- she practically picks it up and carries it to the finish line. The scenes without her are weak, the scenes with her are wonderful.
Nice iteration of a "really smart" zombie film. Recommended.