“The Kindergarten Teacher” is not who you think she is. That’s the biggest lesson of director Sara Colangelo’s gripping new film, something halfway between thoughtful psychoanalysis and nail-biting thriller. In this Netflix original, a remake of a 2014 Israeli film of the same name, Maggie Gyllenhaal stars as Lisa Spinelli, an enthusiastic educator whose obsession for the gifts of her most prodigious student quickly spirals out of control.

Lisa’s life is nothing exceptional. She teaches kindergarten in New York City, attends poetry night classes as a hobby, and returns home every day to her run-of-the-mill marriage and two ordinary kids. However, the exceptional finds her when she comes across one of her quietest students, Jimmy, absent-mindedly composing remarkably profound poetry on the spot. Lisa immediately recognizes his skill—and so does her poetry teacher, after she presents Jimmy’s poem in class under her name. The teacher considers it a step up from her usual work, and Lisa realizes that she’s discovered a six-year-old with rare talent.

Lisa begins to talk to Jimmy during recess, naptime, or any opportunity she can get, trying to fan the flames of his gift, which she believes is being smothered by a bad family situation and an ignorant father. However, Jimmy also seems to give her respite from the doldrums of family life: Lisa thinks her two high-schoolers are embracing mediocrity, and Jimmy’s promise provides her with an escape and an outlet for her hitherto fruitless passion for art. It soon becomes unclear if her motivations are purely altruistic or the result of something deeper and more selfish, something even she doesn’t recognize in herself until it’s too late.

What’s so remarkable about Gyllenhaal’s performance is how easy it is to sympathize with Lisa. She’s just like the everyday heroes teachers always are in the movies: caring, thoughtful, steadfast and high-principled. In a world that can seem saturated with the average, it’s hard not to understand her desire to keep Jimmy’s spark lit. Gyllenhaal transitions seamlessly between the polar opposites of her character in a spellbinding performance both moving and appalling. She transforms Lisa’s steady descent into a tragic demise, a fall from grace, something spectacular and deplorable all at once.

Gyllenhaal is a chameleon, “The Kindergarten Teacher” her ever-shifting backdrop—a mosaic of kindness and hope, heartache and horror. The film is an illuminating portrait of what lies beneath the surface of patient idealism. It begs the question: how far will we go to keep our lives bright?