Can the Boys Identify the International Fugitive in Time?

When a newspaper article warns of an international art thief close by, Gary determines to notice all clues this time. He does not want to be tricked again.

The next day, the Fitzpatrick family boards a train to Chicago, hoping to find out more about the surgeon who amputated Gary's leg. As they travel, the brothers suspect that one of the passengers is hiding something. Why is the artist so interested in the family's conversation about Nehemiah in the Bible? What are his intentions with the old cup at the museum?

From the train to the doctor's office to the museum to the lake, the boys sense that the art thief may be close by. But if they find proof, will it be too late to save the valuable cup?