David Roche, a young double agent, is assigned to recruit British Intelligence Chief Dr David Audley into Soviet service. It isn't long before Roche begins to doubt the information he has been given . . . and it isn't long before he sees how he might use than information to free himself of his obligations to both sides.
Roche joins Audley and two friends at an ancient tower in the French countryside, and also meets with Lady Alexandra Champeney-Perowne - who shows him why it is so vital that he get out.
And out he goes, in an exciting denouement involving the KGB, British Intelligence and - out of the blue - a team of Algerian terrorists.