Josephine Bell was also a physician, so not surprisingly, her novels often feature a strong medical component, not the least of which were two of her doctor-protagonists. She also featured poison and other unusual methods of murder prominently in her plots. Bell and her family were experienced sailors, and the author drew upon this knowledge, too, using many vivid passages in her books that relate to the water and to various nautical details.
Water is certainly at THE PORT OF LONDON MURDERS from 1938, specifically as the title suggests, the port area of London's River Thames. It's a tough neighborhood, but the death of one Mary Holland is still a bit of a shock, even though it appears at first to be a suicide by Lysol poisoning. Tell-tale needle marks on the victim's arm lead Detective Sergeant Chandler to suspect murder tied into a drug ring—which seems even more chillingly apparent when Chandler disappears shortly after he starts to investigate, right before he's due to testify at the inquest. It's up to Inspector Mitchell of Scotland Yard to unravel the layers of deception and addiction that are exploiting rich and poor alike in a way that hasn't changed much in the seventy years since the book was written.
Bell is particularly good with settings, even the squalid ones that pop up in the novel, no doubt witnessed first-hand in her role as a physician who saw people from every walk of life. Her take on the state of medicine in her day was often somewhat bleak, as in this passage from the book—again, as true today as it was in 1938:
"For the great majority of these cases, too poor to have a doctor of their own, there was little he could do...Dr. Freeman could encourage them with a bottle of medicine and help them with a pint of milk a day, but it was not in his power nor that of anyone else to effect a lasting cure of their complaints. There were others, too, not old, but equally hopeless, who attended the dispensary as regular visitors; those struck down in youth or middle age by tuberculosis, rheumatism, heart trouble, and a number of more rare diseases. They had come to the end of their resources, their insurances, and their capacity for earning. The hospitals could do nothing more for them, but they still lived, in the worse possible surroundings, and the Public Assistance saw to it that they did not die too soon."