The Chalon Heads — Barry Maitland

When Scotland Yard detectives David Brock and Kathy Kolla are summoned to Cabot's, a venerable dealer of rare stamps, they expect a simple case of theft and a pleasant digression from the usual sort of wrongdoing encountered in the Serious Crimes Branch. Instead, they find something far more serious: the wife of Sammy China, an unsavory figure from Brock's past, has been kidnapped. But the strange part is that the ransom notes are decorated with rare and valuable Chalon Head stamps of the young Queen Victoria -- to whom Sammy's wife bears an uncanny resemblance. The duo soon find themselves in a most disturbing dilemma: Can they find Sammy's wife when they can't trust anything Sammy tells them?