Maria Merryweather becomes an orphan at age 13, upon her father’s death in 1842. She is sent to the Moonacre Manor somewhere in the west of England, accompanied by her governess Miss Heliotrope and dog Wiggins. There she finds herself in a world out of time. Her cousin and guardian Sir Benjamin Merryweather is one of the “sun” Merryweathers, and she loves him right away, as sun and moon Merryweathers do. Maria discovers that there is an ancient mystery about the founding of the estate.
She is aided by wonderful people and magical beasts, but it is only by self-sacrifice and perseverance, too, that Maria is able to save Moonacre, right the wrongs, reunite lost loves and finally bring peace to the valley.