Behind the Screen (Mason Falls Mysteries)

Hannah's sister, Alexis, has been acting different lately. For one thing, she's constantly on her phone when she never used to care that much about it. But after Hannah discovers that Alexis has developed a relationship with a boy she met online, her strange behavior starts to make sense. What's worse, Alexis plans to skip out on college to run away with this guy. Hannah teams up with her best friend to find out more about the online stranger. What if he isn't who he says he is?