I will be posting this out of chronological order, as the book skips back and forth between Cinders and Scarlets view, but I thought it would be easier to keep track of the story by posting their sections separately.
Cinder has been imprisoned and has been promised to Queen Levana to take back to Luna by Kai in order to have peace between Earth and Luna. When we first meet up with Cinder again she is escaping prison with the help of her newfound Lunar persuasion (thanks to Dr. Erland since he removed the chip on her spine that had been implanted to mute her abilities when she was little) and she makes the guards put her in a cell closer to the exit.
While escaping she accidentally enters the wrong cell through the roof and ends up in a room with Carswell Thorne, a thief. He tells her he has a ship in a hangar nearby that they can escape in. She agrees to take him with her to get the ship.
They escape just barely and Cinder installs Iko's personality chip into the ship to be the auto control system since the ship's is on the fritz. Their power core is almost dead too and they know they must return to Earth soon to get another one, but are afraid to since they are on every most wanted list on the planet now.
In the meantime, Levana is enraged that Cinder has escaped and tells Kai that if she isn't found there will be repercussions and he knows this means she will have the excuse to go to war that she has always wanted. What he doesn't know is that Levana and her thaumaturges have been breeding an army of Lunar wolf hybrid people for battle. They are pretty much werewolves who still look human other than fangs and glowing eyes.
Cinder and Thorne have decided to go to France and find Michelle Benoit, who Dr. Erland told her had helped her escape Luna when she was little and Levana tried to kill her in the fire. They arrive at Benoits farm only to see that it's been ransacked and she's not there, but Cinder has vague memories creeping back and finds a hidden door in the barn that leads to the room where she had been kept in suspended animation for the years they were trying to repair the fire damage and turn her into a cyborg.
They go to the nearest town to get a new power core and are attacked by one of the wolf hybrids. They get away by trnquilizing the wolf with Cinders handy new tranq gun that Dr Erland had installed in her new hand. I don't know if it needs mentioning, but he made a new foot as well and gave it to her for her escape from prison after she lost her foot running from the queen during Emperor Kai's coronation.
Lunar wolf attacks begin taking place all over the world under Levanas bidding. Thousands are killed, and in order to stop it, Kai calls Levana and tells her if she will call off the massacre he will marry her and make her Empress. He knows due to Cinders warning at the coronation that Levana plans to kill him after they are married so that she can take over the Eastern Commonwealth and the rest of Earth, but he sees no other choice.
Thorne and Cinder find Scarlet and Wolf and Cinder tranquilizes Wolf, thinking he's trying to kill Scarlet. The rest of the wolves come after them including the thaumaturge, but Cinder manages to take control of one of the wolves and has him carry Wolf onto their ship to get away. The thaumaturge tries to stop them but Scarlet finds a shotgun amongst Thornes stolen cargo in the ship and shoots and kills him. The remaining wolves scatter and aren't as coordinated now that the thaumaturge isn't controlling them and Cinder, Thorne, Scarlet, and Wolf take off back to orbit to decide what to do.
Cinder sees the news broadcast where Kai announces his engagement to Levana and decides to go to Africa and meet up with Dr Erland after all to follow his plan and take her rightful place as heir to the lunar throne. She doesn't want to be a princess but knows she has to stop Levana somehow. Wolf tells her that just by taking control of one of the wolves with a thaumaturge present has proven that her abilities are stronger than the queen's, as even the queen couldn't control them since they had been bred with the wolf pack mentality of loyalty to a thaumaturge.
Scarlet's story begins with her being frustrated that the search for her missing grandmother has been called off. The police think that she took off on her own since no signs of foul play are shown and her ID chip was left behind, which the cops say people always do when they don't want to be found. Without any evidence they are forced to believe she has taken off rather than being kidnapped but Scarlet knows her grandma wouldn't leave like that.
Scarlet goes to finish her produce drop off at the restaurant and her friend Emilie starts talking to her about the handsome street fighter that she has a crush on that keeps sitting in her section.
Everyone inside the tavern is making fun of Cinder on the news broadcast. Frustrated with her day, Scarlet gets on the bar and begins a speech that they don't even know if Cinder did what the reports say she did, she's only 16 and they need to give benefit of the doubt etc. One of the drunk people says Scarlet is going crazy like her grandma did and she attacks him. The street fighter named Wolf comes to her aid and as she's leaving the tavern he asks her for a job on her farm. She notices a strange tattoo on his arm of letters and numbers as she's talking to him, and although she feels sorry for him she tells him their staff is currently full. He tells her if she changes her mind she can find him at the fights at one of the abandoned farms nearby each night.
When Scarlet returns home, her dad is there ransacking the house and saying that her grandma was hiding something and he has to find it. It comes as a shock to Scarlet to see her dad, since he abandoned them when she was younger a few years ago in favor of a wild lifestyle of drinking and chasing women.
Although she can tell he's lost his mind, she gets enough out of him to know that a group of people have been torturing him in front of her grandma to try to get some kind of information from her and they dropped him off at the house when they saw it wasn't working and she wasn't telling them anything. He tells her that the only thing he remembers of the people is a weird tattoo on one of their arms consisting of letters and numbers. Scarlet realizes it's Wolf and goes to the fights to find him.
He tries to tell her it wasn't him and there are others like him, but the police come to break up the fights and Scarlet loses Wolf in the confusion. He shows up at the house the next day to tell her even though it wasn't him, he knows it was the other wolves that took her and he will help her find her grandma. She asks if he knows their motives and he tells her no, because he took off from the pack a while ago to live on his own. Although still not trusting him, it's the only solid lead she has so she agrees to go with him. They go to the barn since they can't find her dad and he's rifling through all the items in the barn still looking for whatever it is the wolves wanted. Wolf sees her dads necklace and realizes it's a wolves tracker and tells Scarlet they are tracking her dad. Her dad admits that the only
way the wolves would let him go from the torture was if he found whatever the grandma was hiding
and brought it to them. Scarlet is furious that he abandoned her grandma from his own cowardice and now the wolves know she's there too since the tracker has a mic. She sends her dad away and tells him she never wants to see him again and she and Wolf head for Paris to the wolves headquarters to find her grandma.
While on the train there, a letumosis outbreak happens and the train is quarantined so she and Wolf jump off before it stops to avoid being held up and start walking through the woods waiting for another train to come that they can jump onto to take them to Paris. A charismatic boy Scarlet met on the train while ordering food shows up in the middle of the woods with them, claiming that he smelled their cooking duck they caught and couldn't resist. Warily, Scarlet invites him to join them and realizes from the exchange of words between them that he and Wolf know each other. It turns out to be Wolf's brother Ran, a lowly omega of the wolves who wants to kill his brother to gain a higher standing with the pack. There are three classes of wolves; alpha, then the betas, and then the omegas. If an omega can overthrow a beta then he can gain that position. Wolf and Ran fight and Wolf almost kills Ran but Scarlet shoots Wolf in the arm to make him stop before he does, thinking that Ran can give them info about how to save her grandma. Wolf, shocked that Scarlet shot him, stops but tells her they won't get anything out of Ran since any way they could torture him wouldn't be as bad as what the pack would do once they found out he revealed information and Ran knows that.
Scarlet still doesn't want to kill Ran and they decide to leave him there and they can make it to Paris and rescue her grandma before Ran gets there to rat them out to the rest of the pack.
They make it to the headquarters, and a thaumaturge is there named Jael who congratulates Wolf for bringing Scarlet to them. He calls Wolf "Alpha Kesley" and Scarlet realizes she's been betrayed. Wolf reveals the tattoo doesn't stand for Loyal Soldier to the Order of the pack, but rather Lunar Special Operative.
They throw her in a jail cell, and later one of the wolves comes and tells her they'll take her to see her grandma now. She is taken to a room where her grandma is sitting and she begins questioning her to make sure she's okay. It all turns out to be a Lunar glamour though, and it's Ran who is sitting there and not really her grandma. She realizes this when Jael has Ran drop the glamour.
Jael tells Scarlet that they no longer need information from her grandma about where Princess Selene could be (it had been revealed that her grandma is Benoit by Wolf, hence why they captured her to begin with). The search for the Princess had been called off, now that Levana knows it's Cinder and is going after her, but Jael is keeping Benoit now because he found out she is immune to their glamour and is experimenting to find out how, as there hasn't been an Earthen immune to it before and he wants to know how. Although he doesn't know it, it's because Benoit has one of the chips implanted in her back like Cinder had, knowing that one day she may need to be able to overcome glamour if the Lunars ever found her. Jael thought Scarlet may possess the same gift, but since she doesn't, they make plans to torture her in front of her grandma, hoping her grandma cares more about her than she did about her son. This will have to wait though, as the attacks on Earth are supposed to be tonight, ordered by Levana. Jael asks Wolf to lead the attack and he says he will.
Wolf goes to Scarlet's cell and kisses her against her will, but she stops struggling when she realizes it's a chip that he's placed into her mouth that is a cell key. He quietly whispers so that the cell guards outside won't hear that she is to use it the next night while the attacks are happening as there will be limited guards left at the headquarters while the fight is happening.
She does and finds her grandma, who is close to death. She tries to rescue her but Ran has come to find Scarlet, knowing that she is Wolfs weakness and that if he kills her he will hurt Wolf and feel the satisfaction of vengeance for Wolf almost killing him before. Ran kills her grandma and captures Scarlet. He is about to kill her when Wolf shows up to save her. Wolf kills Ran, but his wolf instincts are so strong at the moment that he lunges at Scarlet and is hovering over her with teeth bared when Cinder comes along and shoots him with the tranquilizer. The rest, of course, is tied in to the previous section with Cinder's story.