Warning: This column contains disturbing language. I cannot imagine any parent in Canada thinking about Rehtaeh Parsons without being filled with an icy dread. Parsons, that young Nova Scotian, raped then cyberbullied into extinguishing her life nearly a decade ago. The girl who came of age when rape culture was treated as a banality. Whose death shook a nation and led to some changes in law. Hold our babies close and may they be protected from such grotesqueries. That heinous past makes the appearance of her father, Glen Canning, in a new documentary a haunting moment that crystallizes the calamitous...