Inês Cardoso has uncovered something in the walls of Porto that someone is willing to kill to keep hidden.

Hired to restore a seventeenth-century devotional panel in the city's oldest church, Inês strips back two centuries of overpaint and finds handwriting beneath it: a twelve-line verse in the meter of Portugal's great prophet of return. The discovery should be extraordinary. Instead, a city official who had been asking questions about the commission turns up dead on the riverside — an old symbol drawn in iron gall beside his body.

The verse belongs to a tradition of messianic belief that has been building toward a specific moment for four hundred years, and someone has spent decades engineering that moment for reasons that will reshape everything Inês thought she had found. The question is no longer what is hidden in the panel, but who placed it there, and what they will do before she can prove it.

If she cannot reach the truth before a very public unveiling, a forgery built into old stone will be presented to Porto as a genuine historical discovery — with consequences that reach far beyond the church.