There are some interesting ideas here but for the most part, Chain Reaction is a dud.
Eddie Kasalivich (Keanu Reeves) is an experimental physicist at the University of Chicago working under the direction of Alistair Barkley (Nicholas Rudall) on a method to convert water into energy without any residual pollution. I didn't quite get the science, but he eventually stumbles onto the right set of frequencies that'll enable his research group to use a glass of water to power the entire city of Chicago for several days.
You can imagine what would happen in the real world if such a discovery was made. In the movie, that's what happens: lots of confusion abounds, but essentially Eddie and his love interest Lily Sinclair (Rachel Weisz) are framed for spying; the entire lab is levelled in a mysterious explosion; and some conspirators, led in part by Paul Shannon (Morgan Freeman) are after the frequencies to use for their own nefarious purposes.
Morgan Freeman has a great deal of intensity that's mostly wasted in the film since its focus is primarily on the chase scenes. Reeves is again well-cast in this role as a geeky doe-eyed machinist who doesn't quite understand why he's in trouble.
Chain Reaction is a good time-killer. The film is fast-paced and there's a certain amount of tension as Eddie and Lily are chased across the country by powerful people, but you'll never really comprehend why.