It has been two years since amateur sleuths Lucie and Avalon tackled three crimes that shocked everyone in their town of Wesley. Now that summer is coming to a close, the girls decide to head by train to the North Shore of Lake Superior to visit Lucie’s grandparents.

Not long after the girls arrive at Lucie’s grandparents’ home, they decide to take a walk around the town’s historic district. Fueled by curiosity, the girls enter an unlocked abandoned shop. As they dig through the boxes inside, Lucie and Avalon make a frightening discovery. After the police are called, the girls return home where they soon learn that what they found is just the beginning of a sixty-year-old complex mystery that is about to unravel and reveal a shocking truth to the world.