Cherry St. Croix is an orphan and the heiress of her family's fortune. While her father was not wealthy, but Cherry's guardian has managed the estate well and Cherry will be well off when she comes of age. Since she is not yet 21, she is under the power of her mysterious guardian, Oliver Washmore, and her chaperone, Frances Fortescue. Fortescue, Cherry, her maid Zylphia, and her servants Mr. and Mrs. Booth live in the St. Croix manor house in upper London.

By day, Cherry tries to be a respectable miss in London's high society. Her father's reputation as the Mad St. Croix has turned many people against her, though, and her unconventional ways are sometimes mocked even in the newspapers. The only thing that keeps her from being shunned is the fact that Earl Cornelius Kerrigan Compton has taken an interest in her. Unfortunately, the Earl has left London without telling Cherry, and she is convinced that he was just toying with her. Her chaperone tries to convince Cherry to marry the Earl, but she has many secrets from him and she does not want to lose her independence to any man.

By night, Cherry is a Collector--a collector of bounties for money in lower London. This is dangerous work, especially for a woman, and she does her best to disguise herself as she tries to solve the mysteries her father left behind in the first book. Instead, she runs into a murderer who is savagely killing prostitutes. She tries to chase him, but he disappears into the poisonous London fog.

Later, it appears that Cherry has one ally in the High Society: Lady Rutledge, who offers Cherry a chance to solve a mystery in order to gain the Lady's respect. Cherry accepts, but she will have to look for clues in the dangerous lower London.

Cherry is a flawed character; she suffers from night terrors and uses opium-based laudanum so that she can sleep. She is also addicted to opium, which she cannot currently afford with her limited allowance. It's one of the reasons why she hunts bounties. She also seems to be a manic-depressive, and in this book she fixates on trying to solve the mystery the Lady gave her. Nothing else matters when she is focused on that. The people around her are dear to her, but she can still be quite selfish at times. She also considers herself intelligent and capable, but she doesn't behave in a corresponding manner. She shares an interesting relationship of mutual respect with Zylphia, her maid. Zylphia helps Cherry on her collecting trips. As a former prostitute, Zylphia has a lot of contacts in that world. She is also of mixed race. Cherry knows that Zylphia has been sent to her so that Zylphia can spy on her, but they have an arrangement about that. Unfortunately, the characters remained quite distant to this reader.

The author imbues the book with dark atmosphere and a keen contrast between the High Society and lower London. In higher London, the rich and powerful attend balls and live in manor houses. In lower London, poor, desperate people live in the middle of polluted, lung-damaging fog, and most do not have the money to buy respirators to protect themselves. The evocative descriptions make it is easy to imagine the places Cherry goes.

London, in this book, has been literally divided into upper and lower parts. Those who can afford it live in upper London, which has been raised with accordion girders above the polluted smoke and fog. Different districts are joined with walking bridges and people also use flying gondolas powered by aether.

The scenes among the High Society tend to be somewhat slower than the scenes set in lower London. Overall, the book is fast-paced and ends in a cliffhanger that changes Cherry's life, and terrible things happen to Cherry.

The writing style is somewhat convoluted, which fits the setting but can be hard to decipher at times. It can also be difficult to figure out the full back story without having read Tarnished, as all of the mysteries introduced in the first book are left open-ended. Gilded is the second book in the St. Croix Chronicles, and I recommend reading Tarnished first.