Watch TV Series Pretty Little Liars: Original Sin HBO Original Online Free. Twenty years ago, a series of tragic events almost ripped the blue-collar town of Millwood apart. Now, in the present day, a group of disparate teen girls — a brand-new set of Little Liars — find themselves tormented by an unknown Assailant and made to pay for the secret sin their parents committed two decades ago…as well as their own. In the dark, coming-of-RAGE, horror-tinged drama Pretty Little Liars: Original Sin, we find ourselves miles away from Rosewood, but within the existing Pretty Little Liars universe — in a brand new town, with a new generation of Little Liars.