It seems likely that this movie draws from many other films with similar subjects; it’s a standard drama centered on an unusual group set on exposing a company ignoring the environment. Brit Marling, involved both in front of and behind the camera, plays "Sarah," who's sent undercover within this collective. As she spends time with them, grasping their beliefs and goals, she finds herself increasingly conflicted, particularly when it seems clear that one of their targets is truly as bad as they claim. The other actors are acceptable – Toby Kebbell and Alexander Skarsgård deliver solid performances – but generally the film feels quite lackluster. Marling doesn’t manage to generate much excitement, nor does the writing, which is very straightforward, though there's a sense of resolution near the conclusion; ultimately, I didn’t connect with any of the characters and felt somewhat restless during its nearly two-hour length. A worthwhile subject matter isn’t automatically a good film, and this one would have required considerably more imagination than it provides.

Source on TMDB