 The pediatrician determines a heart noise with Paula. The film accompanies Paula and her mother to the necessary cardiologic investigations, a heart catheter investigation as well as to her heart surgery and the following stay in the clinic up to their dismissal. Structure and disease of the heart as well as all cardiologic investigations like e.g. ECG, echo-cardiogram and heart catheter are explained. Also the operation and the stay on the intensive care unit are represented sympathetically.