SPOILERS!!!
A cop tries to find a murderer, only to find that it's his grand-daughter, travelling backwards through time, trying to prevent a future civil war by killing people in the past (our present) who would propagate the *ideas* that would ultimately kick the war off.
Though the movie kept me entertained — until the last 30 minutes or so — it was ultimately very disappointing. It's an impoverished, childish version of the completely awesome [Travelers](https://en.wikipedia.org/wiki/Travelers_(TV_series)). That the whole movie should be reduced to a single bullet point: that some ideas don't deserve to exist — is puerile and superficial. It does no justice to any of the complex arguments both for and against free speech (however you define it), and it leaves the audience with intellectual blue balls.
Some people have labelled this movie as being about "social justice", but it isn't really. If it was, they would have focused on that, and not on the murder and mayhem, nor would the lead have been a white male cop.
This is 115 minutes you won't get back, ever.