Sixteen-year-old Gemma is on your average family excursion to Vietnam for an art show when she gets into a fight with her mom at the airport and storms off to get some coffee. While there, this creepy guy who's been following her since she left her hometown of London shows up and offers to fund her caffeine fix. He then walks away with her cup to put sugar in it. Um, you probably shouldn't drink that, Gemma.
Ah, but Gemma does drink the coffee—and yes, it's drugged. The guy changes Gemma's clothes and makes her wear a wig, and then he gets her on a plane to Australia using a fake passport. Then, he drives her to this house in the middle of nowhere with a bunch of rocks and scary outbuildings. Really, the whole thing looks like the set of a horror movie.
The kidnapper, a bad dude named Ty, tries to get Gemma to like him and be excited about living in the middle of the Australian desert forever, but for some reason (we can't imagine why), she just can't get too stoked about this. In fact, she's totally terrified of him. As if kidnapping her didn't make him creepy enough, Ty tends to have a lot of weird mood swings, episodes of violence, and dreams where he screams in his sleep. He also spends a lot of time in one of the outbuildings, which makes Gemma think he's really just waiting for the right time to kill her.
Ty starts revealing a lot about his past to Gemma. He tells her that his mom abandoned him when he was little and that he lived in the Australian outback with his dad for most of his childhood. Then, his dad disappeared, and Ty was taken away to the city and put in foster care. Since Ty was super attached to the natural environment he lived in, this was a huge cultural and emotional shock for him. He got another shock years later when his mom contacted him and said she wanted him to come live with her in England. When he went there to try to find her, though, she seemed to have disappeared.
It was also during this time that he first met Gemma. Wait—these two have a history? You bet they do, even if Gemma is not yet aware of it. See, they met in a park when Gemma was 10, and for the next few years, Ty began keeping an eye on her, even rescuing her from a perverted classmate who tried to corner her in the dark on a walk home from a party. At that point, Ty began crafting a plan to take Gemma away from her conventional yuppie life in London and bring her to Australia to live with him.
Gemma is understandably creeped out by this and keeps asking Ty to let her go. Of course, he's not having any of that. At one point, after discussion of the topic gets serious, Ty agrees to let Gemma run away and see how far she can get. He does this, however, knowing there's no possible way she can survive alone in the desert. In short, Gemma crashes Ty's car into the sand and ends up stripping off her clothes and walking through the desert until she passes out.
Ty rescues her, and from that point on, things start to improve between them. Gemma starts to trust him more, and he even shows her the paintings of the Australian landscape he's been doing in the outbuildings. Slowly, Gemma realizes that she's grown dependent on Ty and even likes him. One night, they watch the sunset illuminate one of his paintings and then fall asleep in the sand together, and Gemma actually feels safe.
Then, just like that, things go bad again. Gemma is bitten by a snake, but while Ty has antivenom on hand, it doesn't do the trick. He has a choice to make—try to cure Gemma with Australian voodoo medicine that might kill her or take her back to civilization, turning himself in in the process. Ty decides to take Gemma to an airstrip, where she's flown to a hospital. He agrees to come along with her because she begs him to, knowing this means it's the end of the line for him. He's arrested when they land.
As Gemma recovers from both her snakebite and the ordeal in the desert, she struggles with some really confusing emotions. Even though she's back with her parents, she really just wants to be with Ty and finds the city environment jarring and loud. She's visited by a wide array of counselors, all of whom think she has Stockholm syndrome. As a way of working out her issues, a psychiatrist tells her to write a letter to Ty—the contents of which is the book we've been reading.
While Gemma debates lying to the jury and saying that she and Ty plotted to run away together, she eventually decides she has to tell the truth—but also include in her testimony the compassion and kindness Ty showed her. She hopes that once he gets out of jail, he can be the tender person she knows is in there somewhere.