A hidden inscription on a 15th-century Flemish painting triggers a dangerous investigation into a centuries-old murder. Julia, a young art restorer, discovers the cryptic message "Who killed the knight?" while cleaning a masterpiece by Pieter van Huys. As she attempts to decode the painting's hidden chess game, she finds herself entangled with a circle of academics, antique dealers, and chess enthusiasts who are willing to kill to protect the secret. The narrative unfolds through a blend of art history analysis and high-stakes suspense, forcing Julia to navigate a world where the past and present collide with lethal consequences.

This novel is widely regarded for its intricate plotting and the author's ability to weave complex art history into a compelling thriller. Readers often note the intellectual depth of the narrative, which challenges them to solve the mystery alongside the protagonist. The atmosphere is frequently described as dense and scholarly, providing a unique experience for those who enjoy puzzles and historical detail. The interplay between the chess game and the unfolding events creates a sustained tension that keeps the reader engaged throughout the investigation.