The Black Windmill
Leigh Vance (screenplay), Clive Egleton (novel)
Michael Caine as John Tarrant, Donald Pleasence as Cedric Harper, Delphine Seyrig as Ceil Burrows, Clive Revill as Alf Chesterman, Joss Ackland as Chief Supt. Wray, John Vernon as McKee
Major Tarrant, an agent of Cedric Harper, learns his son has been kidnapped and he must turn over a cache of diamonds the Department has obtained. Tarrant learns even more than he already know how little he can trust his superiors.