V.C. Andrews' Hidden Jewel

Ruby arrives just to late to learn nanny's death bed secret, presumed relevant to a voodoo curse. Shorty after, one son dies from a snake bite in the garden, his self-blaming twin brother Paul collapses into a frightening condition. Daughter Pearl, a medical student, realizes it's broken heart syndrome, confirmed by a psychiatrist, and rationally reject the voodoo curse, which inspires Ruby to consult voodoo priestess Mama Dede and takes her advice to seek the truth back in grandma's bayou dwelling. Pearl goes after her and the dark truth, teaming up with the family oil company's bright, studly executive John, who even becomes her true lover, braving all dangers -including her mother's creepy 'buyer'- together, while a fall disabled her softy father, and saving both Ruby and Paul.