In Chapter 11 of The Chrysalids, the group is unquestionably in trouble now, and their detection is imminent. How does the author maintain suspense, considering that the reader knows that the group's cover will be blown?
The main event in Chapter 11 is when Petra, unknowingly, sends out a distress call telephathically that is so strong that all of the telepaths feel they must go and answer it straight away. This, of course, is incredibly risky, as the telepaths long ago decided that they must never actually meet physically. David twice in this chapter refers to the "meeting that should never take place" as the telepaths gather around Petra. The tension in this chapter is raised massively when a man called Jerome Skinner follows Katherine and Sally, who come from around half an hour's distance away, to Petra. Even though David does his best to allay his suspicion, he fails to believe their explanation that Katherine and Sally heard the screaming of Petra and the horse. Note how he is described as he leaves:
The man lingered. He still seemed dissatisfied and a little puzzled. There was, however, nothing for him to take a firm hold of. Presently he gave the three of us a long, searching stare, looking as if he were about to say something more, but he changed his mind.
It is clear that he still has massive questions about what happened, and the way that he is described as giving a "long, searching stare" strongly suggests that he is suspicious about how precisely Katherine and Sally knew where to come. Even though this does foreshadow the group's eventual discovery, Wyndham maintains suspense by suggesting that the group have managed to escape detection this time. He allows the reader to believe that, in spite of the risk they have ran, they might have done enough to avoid being exposed.