An oasis in the heart of Kentish Town, Balaklava Street is ripe for gentrification, but then the body of an elderly woman is found at No 5. Her demise seems to have been peaceful but for the fact that her throat is full of river water. For the Met's Peculiar Crimes Unit, led by London's longest-serving detectives, Arthur Bryant and John May, this curious death marks the beginning of a distinctly sinister investigation, and the new owner of No 5 is understandably unsettled by the damp in the basement of her home.