Marlo, a mother of two with another baby on the way, is struggling to cope with the overwhelming demands of parenthood. Her husband, Drew, is loving but largely absent due to his demanding job, leaving Marlo to deal with the chaos mostly alone. Already exhausted and on edge, Marlo’s stress is compounded by her son Jonah’s peculiar behavior, which requires extra attention and patience, adding to her day-to-day challenges. When Marlo gives birth to her daughter Mia, the added pressure of a newborn pushes her to a breaking point.

After a particularly hard day, Marlo's wealthy brother, Craig, offers to pay for a night nanny as a gift, suggesting it could help alleviate some of her stress. Initially resistant to the idea of having a stranger care for her child, Marlo eventually relents out of sheer exhaustion. Enter Tully, a young, vibrant night nanny full of life and unconventional wisdom. Tully's arrival brings a breath of fresh air into Marlo's nighttime routine, and the two women form an unexpected bond, as Tully helps Marlo navigate the trials of motherhood with a perspective that reignites Marlo's passion for life.