Bill McGill, a lawyer living in St John's, has been asking himself this same question for more than twenty years, since the day he saw or thought he saw- something large and monstrous rise up out of the water and pluck a hapless seagull from the air. Today the memory resurfaces as his niece, Esme, finds herself on the wrong side of the law and charged with murder - one that took place on the shores of that very same pond. With solid evidence against her, and a dogged prosecutor bent on making an example of the young woman, Esme's fate is sealed. But her uncle refuses to give up hope. Bill McGill must return to the scene of the crime - and the scene to his own long-ago nightmare vision and learn the truth about what lurks beneath the waves of Twenty Mile Pond.