A surprisingly engrossing and dark tale of a man changing his past, "Butterfly" bases itself on an admittedly ridiculous premise of time jumping and the consequences of it. Ok, so the main setup is more like something out of a "Star Trek" or "Twilight Zone" episode, but the very serious and quite disturbingly morbid at times tone make it a grittier and more adult journey than any episode of either show. Subjects like pedophilia, animal torture, dismemberment, etc. all get a work out and if you're used to thinking of Ashton Kutcher as too clean cut then by the time he gets down on his knees and offers to suck the cock of a gruff prisoner, you'll know this is far from "That 70's Show".
In fact that's the big surprise here, as a serious dramatic lead Kutcher does a great job. There's no silly mugging or sly winks to camera, he and the rest of the cast totally play the material straight which makes all their assorted wild changes credible. The film almost over explores the 'Butterfly Effect' theory, a term coined from the Ray Bradbury short story "A Sound of Thunder" about how a small accident in the past can dramatically change the present. In this, Kutcher keeps jaunting back to past incidents in life to try and improve his and his friends lives but almost everytime there's a sly level of dark humour about how no matter how hard you might want to change something, by doing so there's little chance things will get better (and if they do other things will get worse).
Some of the realised new realities come across almost comically silly, but with the film's frentic pace and the solid but subtle horror undertones, the implausible becomes not just credible but strangely fascinating. The cinematography, score and production design (whose crew probably had a ball coming up with all the different looks/changes to the characters) is all rich and textured with far more care than most films of the genre.
The only real downside is that its so unrelentingly dark and serious, and it exploits many of its dark character traits of violence and perversion well past the point of comfort. As a result it's a bit of a draining experience and certainly not one for the timid or those who are upbeat and positive all the time. Kutcher fans will really be scratching their heads over this one and will probably wonder what to make of all of it by the end. For those who can sit through it though, you'll find a dark and provocative sci-fi themed drama here that's far more interesting than its very early in the year release would have you believe.