As a child, his grandfather would sing him the same song over and over. He sang with a twinkle in his eye, as if hinting at a great secret. As time passed, he came to understand the secret. The frequency of the tune held magical powers. Powers that would enable him to avoid detection. Whenever a new disemboweled corpse was discovered, witnesses would come forward and they said the same thing. That at the time of the murders, they could hear a tune being whistled nearby. When her husband fails to return home on their wedding anniversary, Sylvia Brennan's life alters forever. She moves in with her friend and tries to move on, but one night she finds herself running for her life, hunted down by a maniac armed with a knife and a cheerful tune.