As the winter of 1921 slowly turns to spring, certain residents of Brighton find themselves at the mercy of a poison pen writer, who is spreading rumours and innuendo about the town. Disturbed by the scandal this could cause, Mrs Wilton, one of Clara's first clients, returns to Brighton's first female private detective seeking help. But how can Clara find a person who chooses to remain anonymous? Could the elusive Mrs Prinner be the key?

In the meantime she has other matters to contend with, as Inspector Park-Coombs of the Brighton Constabulary is convinced there is a traitor among his men. A mysterious accident and missing evidence suggests someone on the inside is giving the criminals of Brighton a helping hand. They might even be responsible for Clara's near fatal encounter with Billy 'Razor' Brown the year before. Park-Coombs needs an unbiased outsider to investigate on his behalf, but is Clara in over her head? And could the traitor be someone she already knows?

Torn between her two cases, Clara must dash across Brighton in a frantic quest to find the truth. In the process she will discover more about the town's hidden underworld than she ever wanted to know and put the life of a policeman in danger. Can Clara reveal Park-Coombs' traitor before it is too late?