Schoolteacher Dan Forester's lottery number just came up. This is not a good thing, since this lottery determines which civilians get to go into the future for one week to fight the invading aliens that have the human race on the edge of extinction. Not many people come back after the week, partly because the arms they get are minimal and the training non-existent. Little does Dan know that the future, and past, of the human race may be in his hands.

THE TOMORROW WAR is trite, predictable, derivative and really rather silly, none of which detracts too much from the fact that it is also quite a bit of fun. A good part of that lies in the undeniable charm of leading man, Chris Pratt. He is innately likeable and so you are rooting for him from the start, even though he can be a bit of a git about his own lack of success. He feels, it seems, as though the world owes him better than the steady job, nice house, lovely family and great friends he has. All of that, though, is turned on its head when the first people come back from the future with dire predictions of extinction.

The set-up duly delivered, it's off to boot camp where we meet a bunch of characters whose names we don't even get time to remember. There's the kind man who seems destined to die immediately, the hardened veteran of numerous tours who you know is going to die and a bunch of hapless civilians who are destined to die. Who's not going to die? Chris Pratt, that's who.

After the quick boot camp tour (and boy do we mean brief) these nameless people are dropped, literally, into the heart of combat. This is the most entertaining part of the film as characters who are unprepared to deal with angry teenagers fail spectacularly to deal with alien killing machines. The aliens are rendered in pretty good CGI and are sufficiently alien and sufficiently deadly to impress. They off the humans quickly and without remorse. There is absolutely no time given to wonder what these things want, other than to eviscerate everyone they encounter. That's actually refreshing.

Following the initial mission, however, things get a lot less refreshed. Dan meets a figure from his present, their past, and a solution to the invasion is found, but it's a solution that has to be delivered in Dan's present, thus wiping out the future that sent people back in the first place. Still, what's one huge, gaping time paradox between friends eh? This and the whole mission to save the world that makes up the final part of the film, is just tired. The fact that it all takes place in an alien spaceship right out of THE THING FROM ANOTHER WORLD hammers home just how unoriginal the whole plot has been. As an extended coda, it undermines the rest of the film, which was shaky to begin with. The reforging of family bonds doesn't make it any easier to swallow.

Still, with Chris Pratt, Yvonne Strahovski and JK Simmons providing the star wattage, that shakiness is considerably shored up. They can all do this sort of stuff in their sleep and there is nothing here to challenge them at all. They provide the glue to keep the house of cards from collapsing. Well, them and some slick action sequences, impressive CGI aliens and a bravura sequence welcoming us all to the future.

THE TOMORROW WAR will soon be yesterday's news, but it is enjoyable enough whilst it lasts.