On the verge of adulthood, the wide-eyed and reserved fifteen-year-old schoolgirl, Adèle, can only imagine the delicate touch, the odd, yet lingeringly fervid feeling of desire, and the vehement outburst of emotions of her first teenage love. Increasingly indifferent to her male classmates after a fumbled sexual experience, instead, Adèle finds herself infatuated with the alluring and intriguingly mysterious blue-haired woman she encounters in the street. Inevitably, the bohemian stranger, Emma, creeps up in Adèle's dreams, haunting her deep and untamed late-night fantasies; however, before long, their youthful friendship will yield to an arduous, yet ardent romance. Undoubtedly, growing up can be hard, and, just like life, love can hurt. Is blue, indeed, the warmest colour?