This chapter gives an account of a young woman suffering from a personality disorder who killed her baby and her psychoanalytic psychotherapy treatment in high security over several years. The focus is on three main areas. Firstly, the severity of her family dysfunction, especially her relationship with her own mother, gradually emerged in the course of treatment and this led to the infanticide also being viewed as a suicidal or even matricidal act as the patient's identifications with mother and baby altered repeatedly. Secondly, the course of treatment also raised particular countertransferential difficulties with this patient who was, at times, extremely hostile and occasionally violent during sessions and these are also described. Lastly, prognostic expectations and hopes for patients with this degree of disturbance are reviewed