Told from Ananka Fishbein's point of view, these books describe the adventures of the Irregulars, a group of girls who join to explore an underground world beneath Manhattan called "The Shadow City."

She has brown hair, is described as chubby in Inside the Shadow City, and thinks of herself as very unattractive.

Her grandfather was a rat lover and invented a way to safely and effectively get rid of them, The Reverse Pied Piper (a device which the Irregulars recreate and use throughout the series).

Although her platinum hair, a height of under five feet, and unhealthily pale complexion are off-putting, she is described as "strikingly beautiful" on many occasions.

Her real name is 'Katarina Galatzina' but this was changed when she was poisoned by her jealous aunt Livia Galetzina, who wanted to take over the throne.

Due to the poison, unfortunately, Kiki is allergic to everything except cafe au lait and a special nutritious gruel that Veruksha prepares for her.

She is first introduced at a Girl Scouts meeting, where she has just "succeeded in refining a particularly dangerous strain of botulism", which is described as a poison that can reverse wrinkles and all signs of age.

She receives a scar on her forehead from an explosion that takes place in Inside the Shadow City.

She forges birth certificates, driving licenses and illegal maps and is also known to have a talent for picking locks.

This leads them to discuss important and often money-making deals and pieces of information with their friends, most of which Oona picks up and uses to help her get more money.

Iris is first mentioned in the series in the first book, as she encounters the Irregulars as they are escaping from the Shadow City.

Her parents travel a lot, and they once brought back a very strong smelling perfume that turns out to keep the rats of the shadow city at bay.