When a strange spaceship arrives on planet Earth, Linguist Louise Banks (Adams) is recruited by the military to decipher their language to see if they are a threat to the planet or not. Along with her they assemble a team of experts to help including scientists/mathematician Ian Donnelly (Renner). Forest Whitaker is fantastic as Colonel Weber but very under used in the film imo.
What happens next is not an action packed thriller but more of a think film similar to the movie Contact on a different plot entirely. You spend most of the film trying to figure out weather the events happening are flashbacks or flashforwards (pretty easy to figure out it's one or the other). Sequence is not important here in terms of the plot.
You find out that the aliens came to Earth to request the help of humans but not until a few thousand years in the future. They leave behind their language which is a means of seeing events in different time order. Not sure I buy the whole thing. That's a problem. It is never said for what the aliens require our help for, nor how we supply that help - just that their leaving their time shifting alien language. See my dilemma here? Are humans to use that language to help them in the future? Then I want to at least know in what way. That is never answerd. Anyway...it doesn't detract from enjoying the film itself but it does leave you with a lot of questions at the end. I wondering if you have to see the film more than once have some questions answered. I'll wait for it to come out on DVD before watching it again. My only other issue was how the heck did Louise breathe in the fog/smoke of the aliens when she entered their chamber? She wasn't wearing any breathing apparatus. Still makes for good discussion the whole time out of order and/or knowing the future etc.
If you want Independence Day then don't go see this. If you liked Contact then I suggest you see this one!