To appreciateNight Moves -- the story of three Oregon-based eco-terrorists intent on blowing up a dam -- you have to be willing to accept a bucket full of unsettling and sometimes unsatisfying ambiguities. Director Kelly Reichardt casts Jessie Eisenberg as an uneasy environmentalist who's committed enough to pursue a destructive form of protest, but doesn't come off as an ideologue. Eisenberg's Josh joins forces with two others: a former marine (Peter Sarsgaard), who has planned the operation and a disaffected young woman (Dakota Fanning). Fanning's Dena may have been recruited because she's considered a good bet for convincing an agricultural supplier to sell enough ammonia-drenched fertilizer to make a bomb. The cause makes sense: The dam provides water for unbridled development, but the characters and their actions don't always add up. Sarsgaard's Harmon lives in a trailer; Eisenberg's character works on a cooperative farm; and Dena has found employment at an upscale health spa. Reichardt (Wendy and Lucy) may want to define the characters by showing how they react to the evolving situation. That means we don't get much background. Reichardt generates a fair amount of tension when it comes to blowing up the dam, but minimizes anything by way of cogent explanation. Josh -- in particular -- remains mysterious, a loner whose motivations may stem as much from confusion as conviction. It's not easy to tell what he wants, probably because he doesn't know himself.