A Sort of Traitors is set in the Haughton Laboratory, a biological research facility in central London, and when the book opens Professor Sewell, the leader of the research team, is on the verge of announcing some important results concerning the control
of epidemics. Before he is able to do so, the laboratory is advised by the government not to publish its work in case it is used by foreign powers for nefarious, non-altruistic means, i.e. as the basis of a biological weapon. Sewell is outraged by the decision but in the eyes of one of his juniors—young, naive, idealistic Bob Marriott—does little to rectify the situation.
Marriott’s colleague Lucy Byrne lives with a man called Ivor Gates whom she had met during the war. They had intended to get married once the conflict was over but an unfortunate ‘friendly fire’ incident effected an alteration in their plans:
“So I joined the army.” Ivor smiled brightly. “And just to show how grateful they were the R.A.F. blew my arms off.”
Having returned to England as an embittered double-amputee with a short life expectancy, Ivor refused to marry Lucy, who thus now acts as his live-in carer. Marriott starts going out with Lucy on a casual basis and through her meets Ivor. The trio discuss the fact that the Haughton is being gagged and prevented from publishing its research. Ivor then introduces Marriott to an acquaintance of his, Bill Brown, who spins a yarn about a body that might be willing to publish the work clandestinely:
“I think it’s called the International Scientific Exchange. I gather that it’s got members amongst scientists all over the world—people who believe that there ought to be no national barriers in science. And it exists for the private exchange of information between scientists.”
The Haughton staff have been placed under surveillance by M.I.5, represented by the bumbling, world-weary and ostensibly ineffectual figure of Mr. Prince, one of Balchin’s most notable minor characters:
“Now, as you both know, some time back we were told to keep an eye on the Haughton Laboratory. It was one of these ‘no trouble’ jobs. We weren’t to do anything, of course. We were just to see that nothing leaked from a place which wasn’t under proper security control, which was part of another building, which might be open all hours of the day and night—and so on. Just one of those little jobs that make us go away and shoot ourselves.”
Balchin even goes so far as to equip Prince with his own set of memorable catchphrases, such as “You never know anything on these jobs” and “We were told there wasn’t to be any trouble”.
Prince wishes to interview Ivor but discovers that he has committed suicide, having by his own assertion ‘scuppered’ Marriott by introducing him to Brown, who in turn is well known to M.I.5. Marriott removes the research paper from the laboratory, with the intention of giving it to Brown, or at least finding out more about the people he is working for. But he then gets cold feet and has just returned the paper to the laboratory when he is discovered by Sewell, who was only working late himself because he was also engaged on a scheme to disseminate the research findings in an underhand manner. Knowing that the security forces are on their trail, the two men hatch a cover story whilst Prince and his men stake out the house where they assume the treacherous act will take place. Marriott of course fails to turn up, and by the time M.I.5 reach the Haughton the paper is safely tucked away again under lock and key and the movements of both Marriott and Sewell can be accounted for.