After the events of the first book, Scarlet Benoit is an 18-year-old girl living on her grandmother's farm in the rural town of Rieux, France.

While delivering fresh goods to one of her loyal but unfriendly customers, her friend, Émilie Monfort, introduces her to a jittery, shy street fighter whose code name is Wolf, who saves her after she makes a speech defending Linh Cinder, the Lunar cyborg who caused chaos at the Eastern Commonwealth's annual peace ball.

She questions him, noting he has burn marks all up his arms from being tortured, and he says that the same people who hurt him have her grandmother because she was supposedly hiding something.

On the train ride to Paris, Scarlet meets a young man called Ran, who Wolf seems to smell on her later.

When Scarlet and Wolf arrive in Paris, he leads her to where her grandmother is being held, but he betrays her and reveals that he is a Lunar Special Operative, a bioengineered wolf-Lunar hybrid soldier who serves Queen Levana.

She recalls Linh Garan, the man who adopted Cinder after her surgery, talking to her grandmother, but doesn't know why she resists manipulation.

They go to Gilles's tavern but are found by the military after being tracked via her dead stepsister's ID chip, which Cinder still had with her.

Her grandmother also tells her that Scarlet is the granddaughter of Logan Tanner, the doctor who spirited Selene to Earth and performed her cyborg surgery, and eventually killed himself after suffering many years of Lunar Sickness.