Marigold Lesley is an imaginative young girl whose father died before she was born. She grew up at her paternal relatives' estate, Cloud of Spruce. Marigold's family includes her loving mother, steely Young Grandmother, shrewd Old Grandmother, her Uncle Klondike who is a former sailor, and her Aunt Marigold, a doctor who saved Marigold's life as a baby. Because of that, the Lesleys named Marigold after her Aunt, and Uncle Klondike married her.
These people made Marigold's life mostly pleasant and carefree, but she nonetheless had her share of adventures, fancies and troubles, many related to the peculiar environment she grew up in. The book relates Marigold's seemingly incurable jealousy of her father's first wife, Clementine; an encounter with a Russian princess; several attempts to be "good"' and a surprising cooking triumph.
One long-lasting product of Marigold's imagination was Sylvia, her imaginary playmate whom she loved dearly and who took the place of many real-life friends for her. But as Marigold grew up and began having trouble with boys, she eventually had to say goodbye to Sylvia and her childhood.