When the details of a man's lonely death in Africa reach the security services in the United Kingdom, the problem is how to deal with the contents of the testimony he had taped. Scant details link this with the activities of the mercenary D'rosario and his secretive multi-millionaire backer J to indicate that something big is in the offing, but what? Paul Marshall begins to put two-and-two together and persuades his boss to undertake an innovative - some would say reckless - strategy for discovering and defeating the unknown menace. What follows is a game of chess, where Paul Marshall carefully manipulates his opponents to prepare the battleground. The battles are fought across medical and maritime theatres of operation. The war is fought largely in the mind.