Unexpectedly, this movie is not at all about the peculiar children and their peculiarities - these are taken for granted, and it's all about helping them survive a deadly threat. Instead, it's all about time travel! And with a quite interesting approach. So as not to bring in any spoilers I will just say it combines two of the different ways the paradox is usually addressed: the rewriting of history once someone travels back in time to make changes, plus a self contained loop in which the time traveler actually becomes part of the one and only history that leads to his time-travel.
On top of that we have little pockets of people living time rewinding scenarios (à la Grundhog Day, but wiht control over it), which makes it all much more interesting, as well as more difficult to disentangle. Have a go and don't miss it!