The next owners of Blackbird House, Katherine and Sam, visit the Cape on a winter day. They’ve come from Boston, where their six-year-old daughter, Emma, is hospitalized for leukemia. The couple is struggling, barely talking to each other. Hearing the realtor talk of blueberries and gardens and sweet peas, they impulsively decide to purchase the place as a summer home. In the spring, Emma returns home, and things improve for the family. Katherine laments the loss of her daughter’s blonde hair, which is growing back in black tufts. Emma embraces it, but when Katherine looks at her daughter, she no longer sees a girl but someone otherworldly, like a sprite or a witch.

That summer, the family, including 10-year-old Walker, go to the house. Sam only sees problems: pipes that rattle, inoperable stove burners, rusty water, and poison ivy. Meanwhile, Katherine pleads with him to give it at least one summer before they consider selling. When they find baby mice in the house, Emma swoops in, saving each one in an egg cup and releasing it in the field. In fact, the girl attempts to save every creature, including spiders, and is enchanted by fireflies.