The mood of the novel is initially foreboding and mysterious, as Mary accustoms herself to her new, lonely Northern English environment in the colossal and craggy Misselthwaite Manor. Readers feel a sense of creeping unease as they discover the nooks and crannies of the old house along with Mary.
Readers are placed at a certain distance from Mary, as the narrator regularly notes that Mary is an "unpleasant" and "disagreeable" child. The choice to make the protagonist of a children's novel so unappealing was certainly an unusual one at the time when Burnett was writing this book. However, this initial discomfort makes the change in mood when Mary later becomes contented and happy even more gratifying for the reader.
When Mary discovers herself, makes friends and settles into her life at the Manor, the mood becomes whimsical, idyllic, and sentimental. The reader feels excited and hopeful as they join Mary in her improvements to personality and outlook. As the book focuses more on the good parts of her life, the mood becomes far happier and less foreboding.
By the end of the book, the mood is almost rapturous, as the characters succeed in all their endeavors and Colin is finally reunited with his father. His wholeness and wellness completely overshadows the sadness and yearning earlier provoked in the reader. By the time Mr. Craven returns to see his son, the "secret garden" is in full bloom, and the writing becomes filled with happy, congratulatory, and golden images of success.
