 Sister Sarah is living in Brazil, 25 years old, a Carmelite, and just about to move back to France. Her twin sister Gaelle has just been released from prison in Paris after serving ten years for killing a child her mother murdered while babysitting. Sarah begins experiencing severe abdominal pain, spawning the curiosity of Joachim a priest and doctor of medicine. Joachim, investigating the illness, discovers, Gaelle is the twin with the physical illness which is being transferred onto Sarah.