When a young woman returns from holiday to find her elderly neighbour dead, she immediately alerts the police. Commissario Brunetti is called to the scene but, though there are signs of a struggle, it seems the woman has simply suffered a fatal heart attack. Vice-Questore Patta is eager to dismiss the case but Brunetti believes there is more to it than that. His suspicions are further aroused when the medical examiner finds faint bruising around the victim's neck and shoulders, indicating that someone might have grabbed and shaken her. Could this have caused her heart attack? Was someone threatening her?