A Crack in the Line, by Michael Lawrence, is a story about two sixteen-year-olds, Alaric and Naia, who discover that they are living in parallel universes. In these parallel universes, they are both living almost the exact same life. They share the same thoughts, moments, and they even look alike. Only one major difference exists between their lives, other than the fact that Alaric is a boy and Naia is a girl. Alaric's mother died in a train crash two years earlier, while Naia's mother survived the disaster. After Alaric accidentally finds a way to travel to the universe in which Naia is living, the two of them work together to figure out why their lives are so similar and why this major difference exists. Events lead them to a major discovery, and their actions result in mistakes, which could ultimately change their lives forever.