Certainly, the ingredients of this Danish film, co-written and directed by Ole Christian Madsen and based on true events, are familiar. 'Flame & Citron' is full of plot and incident, action and romance, loyalty and betrayal. Everyone has a jaunty nickname -- Flame is named for his bright red hair -- and the love of bravery and danger are in the air. What's different here, it gradually becomes clear, is that events are taking place in a compromised moral universe of uncertainty and terror. Venality and calculation, it turns out, do not disappear from the human equation just because a cause is just, and being idealistic may do no more than set you up for being manipulated and misled. Or maybe not. It's almost impossible to tell, and that's the whole point. 'Flame & Citron' opens in Copenhagen in 1944, near the end of World War II, and the scene is quickly set as an unnamed narrator talks about the demoralizing days of the German invasion four years earlier, and reacts with cool disgust at how the Danes who backed the Nazis 'came out of the dark' to show their support of the occupiers. The narrator turns out to be Flame (the charismatic Thure Lindhardt), a 23-year-old introduced giving himself a pep talk, telling himself to 'act with determination' and to remember that his actions are justified. Then he rouses his confidant and driver, Citron (Mads Mikkelsen, Denmark's best-known actor) and we are thrust into the heart of Flame's world. For fueled by an almost visceral loathing of the occupation, Flame has become a highly proficient anti-Nazi hit man, assassinating Danes who collaborate with the Germans. 'Hate seduces you into doing things you never thought possible,' he says at one point, consumed with killing the turncoats one by one and never looking back. Although they're done with tension and a modern sense of edge, these opening sections stay within the norm. Then Flame spies a striking blonde, an enigmatic older woman named Ketty (Stine Stengade), in a restaurant. Their unmistakable mutual attraction sets off a series of events that radically shifts the ground underneath everyone's feet. Ketty claims to be a photographer, but it's immediately apparent that she is linked to the resistance. What's not clear is exactly what she does, who exactly she reports to, what are her allegiances. Crucial questions, but ones that Flame finds increasingly difficult to answer with certainty. At the same time, Flame and Citron's superior, the mysterious Winther (Peter Mygind) changes their orders and insists they begin killing Germans too, starting with a sophisticated officer named Gilbert (a compelling Hanns Zischler) whose conversation turns out to be a minefield. What Flame and Citron, and the audience, gradually come to realize is that they are in an amoral, upside down world where conventional truth is just about unknowable. Obvious-sounding questions like who is on your side and who can you trust turn out not to have verifiable answers. Not only don't the protagonists know the truth, it may be beyond them to figure it out. Also a key underpinning of 'Flame & Citron's' story is a psychologically complex look at what heroism does to heroes. The actions these men take tear at their lives, their families, their very essence. This is especially true of the tormented, permanently disheveled Citron (an expert performance from Mikkelsen, best known as the villain in 'Casino Royale') whose relationship with a wife and child are devastated by his actions. A deeply involving look at people living permanently on the knife-edge of danger, 'Flame & Citron' does more than radically rethink the World War II resistance drama. It's biggest accomplishment may be to make these historical conflicts and dilemmas seem surprisingly contemporary. When someone says of the situation, 'it's not just or unjust, it's just war,' that may be the most modern message of all. 