Thérèse Raquin

Thérèse Raquin is a book by the French author Émile Zola. 
Plot.
An orphan girl named Thérèse Raquin is sent to live with her aunt, Madame Raquin, and her cousin Camille, who is very "sick" with hypochondriasis. When Thérèse is 21, she marries Camille. The three of them then move to Paris.
Laurent, a childhood friend of Camille and an untalented artist, meets Thérèse. The two of them have an affair and plan to kill Camille so they can be with each other. They do this by pushing him off a boat into the Seine River. Everyone believes that Camille's drowning is an accident. Thérèse and Laurent then marry each other. However, they are haunted by their actions. Laurent becomes a talented artist but his paintings remind him of Camille.
Madame Raquin finds out that Thérèse and Laurent killed Camille when they argue with each other. However, she is paralyzed after a stroke and so cannot tell others.
Thérèse and Laurent hate each other. They plan to kill each other. Then they realize each other's plans and kill themselves with poison in front of Madame Raquin.