What is the main conflict in Garden of Shadows by V.C. Andrews?

Garden of Shadows by V.C. Andrews is the final book published in the Dollangager series, but a prequel to the first novel, Flowers in the Attic. Olivia Winfield is a tall, unhappy spinster when she meets Malcolm Neal Foxworth. Olivia believes Malcolm is her knight in shining armor, come to rescue her from her loveless life. However, instead of giving love, Malcolm opens a world of secrets and obsession. Olivia soon finds herself emotionally abused to such a degree that she participates in cruel acts she never thought herself capable of. Garden of Shadows will answer a lot of questions for fans of the Dollanganger series, but it will also reveal a few new truths that will create new questions.