Twelve-year-old James loves mysteries and old books, but nothing prepares him for the real-life treasure hunt hidden in his family's bookshop, The Black Binding. With his best friend, Emily, he uncovers clues linking his missing grandfather to the Monuments Men of World War II and a conspiracy surrounding Vermeer's The Astronomer. Their search leads them deep into Chicago's underground tunnels, where a secret organization lurks in the shadows. Blending history, adventure, and intrigue, The Enigma of the Astronomer introduces young readers to the real-life heroes who risked everything to protect the world's greatest art.