My Sister Rosa
(2016) is a psychological thriller for young adult readers, written by Justine Larbalestier. Blending nail-biting suspense, chilling horror, and intense family drama, the novel tells the story of Che Taylor, an average teenager, and his ten-year-old sister, Rosa, who just might be a psychopath. After a move halfway around the world, Rosa starts playing dark and disturbing mind games on those around her. Suddenly, Che must decide who needs saving: his sister, or those who could end up her victims.
The novel opens as Che and Rosa arrive in New York from Sydney, Australia. They have spent most of their lives moving around because their parents, David and Sally, have failed to start multiple businesses. As the plane approaches New York, Rosa, as usual, is behaving badly. Che doesn't tell his parents about Rosa's behavior since they have convinced themselves her acting out is normal.
Now that he is starting over in a new place, Che sets three goals. First, he wants to spar in a boxing ring, not just train in the gym. Second, he wants a girlfriend. Third, he wants to go home to Sydney. And fourth, he wants to get his little sister's behavior under control. Che worries that she is not just acting out, but is really, seriously, dangerous. He has tried to help her, to teach her right from wrong, but nothing seems to stick. Rosa even once convinced a friend of hers to smother a beloved guinea pig.
The day after their arrival, it is Che's seventeenth birthday. Frustrated with the recent move, he goes to the gym to box. He meets an African American boxer named Sojourner, who goes by Sid. A few days later, they run into one another at the park, but Sid is on her way to church, and Che is on his way to brunch with his family and another family, the McBrunights. Che meets the McBrunights' children, twins Maya and Seimone, who are Rosa’s age, and Leilani, who is Che’s age. Leilani doesn't like Che's clothing or what she perceives as his lack of sophistication. Che doesn't warm to her either, though he is happy that she seems to see through Rosa's fake charm.
A tutor homeschools Che and Rosa. When their parents run late one night, Rosa convinces the tutor to stay so Che can go train. However, when Che returns home, Rosa is missing. Their parents call the police, but Che finds her in the park and recommits himself to teaching her right from wrong.
Che and Sid continue to see each other at the gym; Che clearly likes her. Sid admits that she has feelings for him too, but she can't date him because her faith is important to her, and Che doesn’t believe in God. To get in her good graces, Che agrees to attend church with her.
An argument with his mother sends Che to the gym to vent his frustrations. When his trainer offers to let him spar with Sid, he agrees, even though he has told his parents he wouldn't spar with anyone. Sid roundly beats him. A few days later, they go to church together.
Che also begins spending time with Leilani. Leilani discusses her anger toward her parents…and toward Rosa. Apparently, Rosa and Seimone have gotten to be friends, but Rosa is leaving Maya out of the friendship.
Meanwhile, Rosa knows that Che has been sparring. She tricks their parents into going to the gym, where they catch him in the ring. Outraged, Sally feels she can't trust him anymore. Ultimately, however, David and Sally agree to let him continue sparring.
While his first kiss with Sid distracts Che, Rose has a sleepover with Seimone. Che jolts into the present when Seimone goes into anaphylactic shock, as Rosa hovers over her with the auto-injector. Rosa had fed Seimone peanuts, even though Seimone is allergic. Che administers the injection, and Seimone recovers. Che later tells his father, and David agrees that Rosa's behavior is an issue, but he says the family should deal with it. Che starts to tape conversations he has with Rosa.
After Che has his first sexual experience with Sid, things take a sharp turn for the worst. While Che takes Maya to a tennis lesson, with Rosa and Seimone in tow, Maya collapses into the road and a bike knocks her unconscious. Rosa says that Che pushed Maya, so when Maya later dies, Che is investigated for murder. He gives his lawyer the recorded conversations, as well as his journal, both of which document Rosa's lies. However, someone has tampered with his journals to make it look like he is guilty. The McBrunights request that Rosa, Che, and Seimone have MRIs to look for brain abnormalities. Seimone is normal, but both Rosa and Che have signs of personality disorders. This revelation devastates Che.
Then, newfound footage from a security camera shows that Seimone pushed Maya on the day of the accident. Che is certain that Rosa persuaded Seimone to do it. The twins' parents agree not to press charges against Rosa if the Taylors return to Australia. Rosa confesses to the police that she forced Seimone to push Maya—but Rosa insists that her father put her up to it. And not only that, but she has recorded conversations in which her father instructed her to do bad things and to just make it all look accidental.
Che finally recognizes that David is the truly disturbed one in the family. His father's traumatic childhood and calculating personality come into sharp focus in retrospect. David flees the country under a false name to avoid being charged with a crime. Sid breaks up with Che, and he, Sally, and Rosa end up where they began: on an airplane, en route to yet another new home, trying to keep Rosa in check.