Joelle is about to lose her husband Marc, who has become obsessed with Ketia, a young Haitian woman. Ketia lies to her family to conceal her liaison with Marc. Joelle's friend Diane does not realize that her boyfriend Nazim has never told his Muslim family in Morocco about her. Then Nazim gets a letter that threatens his secret.

Alice Zorn leads readers into the lives of a diverse cast of characters struggling with conflicting cultural values and the demands of intimacy. Set against the busy urban mosaic of Montreal, Arrhythmia is a study of betrayal: the large betrayals we commit against our loved ones, and the smaller ones we commit against ourselves.