Monk's investigation, aided by his wife Hester, reveals a conflict between the two lovers' families over the hasty construction of a vast sewer complex being built to prevent the recurrence of the Big Stink and the typhoid epidemic of 1863. Mary's father, James Havilland, an engineer, warned the Argylls that construction could cause a collapse of tunnels with tragic deaths to the workers. James was found dead in his stable. His death was ruled a suicide, but Mary refused to believe this and has a mission to prove his death was murder to prevent his revelations. Monk's pursuit of the truth leads him and his crew into the dark stinking world beneath the streets of Victorian London.

The author has once again shown her mastery of this period with details of the people and the social conflicts of the time. There are many incidents which show the growing conflict between the poor and those who have gas pipes and other luxuries. The fogbound settings, the work in the tunnels, the horror of the collapse of a section of a tunnel bring the Victorian world close to the reader. One touch of realism, which I found difficult to assimilate, is the use of cockney dialogue.