Arthur, Rosa, Viola, and Luke are known as the "Marsh Four." They are only fourteen years old, but they are already an experienced team of detectives.
The group heard someone blackmailing their classmate Emil’s father, the director of the local museum. In exchange for keeping a secret, the criminal demanded that the director hand over the crates containing exhibits for a new exhibition. It is being heavily advertised and is set to open soon, but its contents are a surprise. If the exhibition opening fails, the director will lose his job and could face trial for the loss of the exhibits. But the exposure of the secret threatens him with the same consequences, if not worse.
Emil begs his friends to help his dad. The "Four" cannot stand on the sidelines and begin a new investigation!
