Leland Fowler, a small-town Vermont attorney, is raising his small daughter alone two years after his wife's death in a car accident when he meets Carissa Lake, a homeopath, and falls in love. He originally seeks her services because of low-grade cold symptoms that won't go away. She attempts to keep their relationship purely professional, but finally advises him to see another homeopath so they can pursue a more intimate relationship.

She starts him on a regimen of highly dilute arsenic solution that helps him immediately. In the meantime another patient of Carissa's, a young family man suffering from severe athsma and allergies, has gone into a coma as a result of eating cashews to which he is violently allergic. The man's wife brings legal action against Carissa since it was under her care that Richard, the patient, started taking a homeopathic solution derived from cashews and apparently was motivated to try the cashews themselves by dint of misunderstanding the "law of similars"--that "like cures like"--that is a central homeopathic principle.

Leland's law firm prosecutes after Richard dies, and Leland is forced to keep his relationship to Carissa secret while he himself struggles with his own doubts about homeopathy. To protect Carissa, because he believes her innocent, he helps her doctor her casenotes. Eventually the case is dropped; Carissa leaves town; and Leland is left to ponder the forces that drive medical, legal, and personal decisions.