Tully (2018)

At first glance, *Tully* presents itself not as a classic whodunit, but as a raw and unflinching dark comedy about the rigors of motherhood. The film follows Marlo (Charlize Theron), a mother of three who is drowning in the exhaustion and despair of postpartum life. The initial mystery is introduced with the arrival of the titular night nanny, Tully (Mackenzie Davis), a free-spirited and seemingly perfect young woman who appears like a miracle. However, as Tully effortlessly restores order and vitality to Marlo's life, a subtle and unsettling mystery begins to form. Who is this woman who seems to know Marlo’s deepest anxieties, her favorite 90s rock songs, and the intimate details of her past? The film masterfully builds a quiet, creeping suspense not around a crime, but around an identity, forcing the audience to question the very nature of Tully's existence. The brilliance of *Tully* as a mystery lies in how its clues are not found in fingerprints or alibis, but in the fragile landscape of Marlo's psyche. The film masterfully layers its narrative with subtle, psychological hints that lead to a devastating and brilliant third-act twist. This reveal doesn't just solve the puzzle of who Tully is; it powerfully recontextualizes the entire film, turning every preceding scene into a clue for a profound and empathetic exploration of postpartum depression, memory, and the fractured self. It proves that the most compelling mysteries are not always about external crimes, but about the hidden truths we conceal from the world and even from ourselves. *Tully* earns its place on this list by using the structure of a mystery to craft a deeply personal and unforgettable psychological portrait.