t’s easy to get lost on the forested campus of Wellesley College, the private all-women’s university a half-hour away from Boston. The blue dot on your phone’s GPS is too small and the light thrown by the storybook lampposts too dim for a New England night in the fog of December. A quiet university campus at 11 p.m. is not the most comfortable place for a woman to walk alone, and so at first, you let the stranger behind you move ahead. But very quickly, perhaps after the third or fourth person has walked on by, you notice that they...