We take a great deal for granted in the 21st c., including the ability to purchase and use over-the-counter drugs without killing ourselves. It doesn't mean they're safe--you can still do serious damage to yourself with aspirin, acetaminophen and a host of other legal drugs, but the dosages are controlled and the contents are labeled.It wasn't always that way. It wasn't until 1906 that the US passed the Pure Food and Drug Act, and A Sunless Sea deals with a period nearly 50 years earlier in Britain, when a first tentative stab was made at regulating opium sales. The novel features police detective William Monk and the other characters Perry's brought to life in this series, and graphically illustrates how far individuals in industry and government may be willing to go when there's profit at stake.This novel will be best enjoyed by regular readers of the series, because of the secondary characters and the roles they play. Other readers may wish to start with earlier Monk books to get a feel for series.