Fourteen-year-old Abbey Sinclair likes to spend her afternoons in the physics lab learning about momentum and gravitational pull. But her practical scientific mind is put to the test when her older brother, Simon, discovers a mysterious path of stones that allows them, along with Abbey's twin, Caleb, to travel back and forth between their world and what appears to be...the future. Unfortunately, they're not the only ones who know about the stones, and they soon realize their lives are in danger from a man known only as Mantis. Abbey, Caleb, and Simon must follow a twisting trail of clues that will lead them from their autistic neighbor, Mark, to a strange professor who claims to know the rules of the stones, and to multiple futures-some of whose inhabitants don't want to stay put. It will take all of Abbey's analytical skills to unravel the secrets of the stones, uncover the threads that tie the futures together, thwart Mantis's plan, and, most importantly, keep her family alive-now and in the future. A Pair of Docks explores Einstein's Theory of Relativity, the meaning of time, the potential for parallel universes, and the boundary between science and witchcraft. It is the first novel in the Derivatives of Displacement series.