When mother Marlo gives birth to her third baby, she wasn't expecting to hire a nanny to help with the newborn. Her brother contracts the services of young Tully as a nanny on Marlo's behalf, however. At first Marlo thinks of having a nanny as an unnecessary indulgence, but as the two women get to know each other better, they begin to form an unexpected bond, although their relationship is not always such smooth sailing.