No fast action here, as spying business is a very slow and tedious affair, as already Somerset Maugham made clear in his early short stories, as that activity mainly tries your patience until it breaks, and that's when the mistakes are committed. Stephen Murray makes a very credible character as the defector from Yugoslavia seeking asylum in Britain and getting employed in an advanced nuclear research centre, where he can be at large doing whatever research he wants and using the results for his own ends, but unfortunately his collaborator is the wrong kind of man, and when he prompts the execution of Murray's secretary, for having found out about their business, Murray declines, and things are messed up. It's a rather ordinary spying story of double crossing and double purposes and the main issue getting busted, and the whole enterprise reaches a rather hasty end, without the original purpose getting fulfilled. But no one dies, and that at least is something in this rotten business where the end always justifies the means and usually get shipwrecked on the way.