Kill or Cure: An Edwina Crusoe Medical Mystery

Mary Kittredge's sixth novel featuring medical sleuth Edwina Crusoe begins with every mother's nightmare: Marion Bailey returns home to find her son Gerry wheezing and ill, one ear severely swollen, apparently from an allergic reaction to pills from the bathroom cabinet. After rushing him to Chelsea Memorial Hospital, she is shocked to learn he has been shot in the ear while playing with a friend - and that his friend, another boy, is missing.
The nightmare gets worse when a promising young physician walks into the emergency room, shoots a security guard, then his wife (a nurse), and finally fires at but misses Gerry Bailey. Two days later, Edwina Crusoe is summoned by the physician's lawyer. The lawyer faces a dilemma: he has been hired by the family of the murdered wife to defend the physician, to plead insanity, but he can find no evidence to support that defense. Edwina's job is to investigate the physician's past for anything that might throw light on his motive for the murders.
As Edwina searches, she begins to uncover a family history with disturbing implications for the physician's defense. Meanwhile, another crisis continues, for Gerry Bailey is too terrified to speak about what happened to him. As the search for his missing friend becomes urgent, Edwina - herself a mother - is moved to offer help to Marion Bailey.