Life becomes more interesting for Ananka Fishbein when, at the age of twelve, she discovers an underground room in the park across from her New York City apartment and meets a mysterious girl called Kiki Strike who claims that she, too, wants to explore the subterranean world.
Fourteen-year-olds Ananka Fishbein, Kiki Strike, and the other Irregulars encounter a Chinese mummy, a ghost, trained squirrels, and old enemies as they try to stop an art forgery ring and safeguard the secret streets hidden beneath New York City.
Life becomes more interesting for Ananka Fishbein when, at the age of twelve, she discovers an underground room in the park across from her New York City apartment and meets a mysterious girl called Kiki Strike who claims that she, too, wants to explore the subterranean world.