While spending the summer at Grandmary's home on Goose Lake, Samantha and the twins Agnes and Agatha decide to visit the island where Samantha's parents were drowned during a storm.
When Samantha's tenth birthday party is spoiled by the boy next door, Aunt Cornelia and her young twin sisters try to ease Samantha's disappointment by inviting her and Grandmary to visit them in New York City.