Murder by an Aristocrat

After a murder at the manor where she's employed, a nurse trades her stethoscope for a magnifying glass . . .

When Nurse Keate arrives at the Thatcher estate to care for a man with a bullet in his shoulder, she's told that he shot himself accidentally-but when the convalescing man is murdered soon thereafter, it becomes clear that the only "accident" was his not being fully killed the first time around. A murderer stalks the manor and yet the rest of the family isn't the slightest bit alarm...