The story begins with Conan, along with his friends from the Junior Detective League, attending a memorial ceremony for a dam that is about to be completed in the scenic mountains of Japan. The dam holds great significance for the local community as it will provide electricity to the region. However, during the ceremony, a prominent businessman named Gentaro Higa is found dead at the dam’s edge. His death is initially presumed to be an accident, as he fell from the dam’s observation deck due to a sudden bout of dizziness.
Soon after, a snowstorm traps Conan and the others in the mountains, isolating them from the outside world. As the storm rages on, Conan becomes suspicious of the circumstances surrounding Higa’s death. He discovers several inconsistencies, including a mysterious message carved into the observation deck. Conan believes that Higa’s death might not be an accident after all and that foul play is involved.
As Conan investigates, he uncovers a web of secrets and a long-buried crime connected to the construction of the dam. He learns that a tragedy occurred fifteen years ago when a group of mountaineers lost their lives in an avalanche during the dam’s construction. Their bodies were never recovered, and their families have been living with the grief and uncertainty ever since.
Conan suspects that the recent death of Gentaro Higa is somehow connected to the past tragedy. He believes that the murderer is attempting to cover up the old crime, ensuring that the dam’s completion will proceed without any hindrance. With the help of his friend and ally, Heiji Hattori, Conan starts piecing together the puzzle.
As the storm intensifies, tensions rise among the trapped individuals. Conan must gather evidence, uncover hidden motives, and unmask the true killer before more lives are lost. He faces numerous obstacles and dangerous encounters as he gets closer to the truth.
