When thirteen-year-old Sammy finds herself with an abandoned baby on her hands, she sets out to find the young mother, who may belong to a gang, and accidentally jeopardizes her position on the softball team.
When fifteen-year-old Peer Ulfsson witnesses the disappearance of his neighbor's wife, rumored to be a seal-woman, he must help protect the baby she leaves behind from trolls, a witch, and other creatures.
Having found a tiny baby in a peanut shell, Larky Mavis calls him Heart's Delight and carries him around as he grows bigger, to the confusion and anger of the adults around her.