What is the significance of the title, The Whisper Man?

It is not uncommon for the novel's characters to whisper, especially in threatening situations. The continued reference to whispering reinforces the idea in the novel that a whisper can be just as threatening as a shout. Take, for instance, Pete’s encounter with Collins: “‘Is there anything else, DI Willis?’ Collins whispered. / Pete took a step away, his heart beating hard” (154). Collins whispers his question to Pete but that whisper causes Pete to fear him more than a shout would have. Note also that Carter, the Whisper Man, gets his nickname because he whispers to the children he abducts.