A British agent's son is kidnapped and held for a ransom of diamonds. The agent finds out that he can't even count on the people he thought were on his side to help him, so he decides to track down the kidnappers himself.
The Black Windmill is a 1974 British spy thriller film directed by Don Siegel and starring Michael Caine, John Vernon, Janet Suzman and Donald Pleasence. It was produced by Richard D. Zanuck and David Brown.
