Elinor Carlisle stands accused of murder. The story begins in a courtroom where she is on trial for poisoning Mary Gerrard, a young woman she was once close to. Through flashbacks, the events leading to the crime are revealed.

Elinor was engaged to Roddy Welman, but their relationship became strained when he showed interest in Mary Gerrard, a beautiful and kind young woman. Meanwhile, Elinor’s wealthy aunt, Laura Welman, was in poor health and was expected to leave her fortune to Elinor. However, there were rumors that Mary might inherit instead. When Mary suddenly dies from morphine poisoning, all suspicion falls on Elinor, who had both a motive (jealousy and inheritance) and opportunity.