Asghar Farhadi's Fireworks Wednesday is, as would be expected, a beautiful, delicate and keenly observed film. It follows Roohi, a wide-eyed bride-to-be, as she gets an education on marital conflict and human complexity on the last day of the Iranian new year. In the morning, she rides a motorcycle through the mountains with her fiancé before trying on a borrowed wedding dress in a cramped bathroom at the cleaning service agency where she works. Then she travels across town for what turns out to be a long day of cleaning for a wealthy urban couple whose house's casual chaos reflects the cracked tension in their marriage. As relational conflicts with deep roots erupt in bursts around her, firecrackers are set off in the streets in anticipation of the evening's fireworks display. She becomes an unwitting observer to a tipping point in the marriage between a frustrated husband and his suspicious, depressive wife. A naturally curious person, Roohi can't help but try to put together the pieces of their conflict and is soon enough dragged in to collect and convey information.

The complexities of marital strife take center stage, but the class differences throughout are just as striking, as Roohi experiences firsthand the casual and seemingly relentless selfishness of the wealthy. Everyone seems to know their place in the social structure without too much fuss, but empathy really only runs one way. As ever, Farhadi observes the action from a cool distance, carefully controlling his frame and the action in it. There is little distraction by way of editing or score as he keeps the focus on the quiet human symphony on screen. His greatest gift, however, is his exceptional knack for directing actors and his keen feeling for human behavior. Each performance feels wholly authentic and considered. Taraneh Alidoosti is touching as the sweet-natured, perplexed Roohi, but special notice should go to Hediyeh Tehrami, who brings sharp precision and deep misery to the highly strung, existentially exhausted wife. Pantea Bahram also excels as her kind, easy-going neighbor and the object of her suspicion, handling even painful confrontations with a smile and a gentle shrug of the shoulders.

With such a finely tuned plot of secrets, lies, insinuations and deductions - false and otherwise - it's a marvel of Farhadi & collaborator Mani Haghighi's writing that none of the characters' actions - big or small - ever feel contrived. Exposition and plot seeds are woven effortlessly into moments that feel spontaneous and full of life, but later turn out to have great bearing on the plot. Farhadi once again proves himself a master at orchestrating minute, and quietly escalating, human drama. Fireworks Wednesday contains moments of genuine beauty and keenly observed human existence. It's also an effective, and affecting, drama that sizzles rather than explodes.