‘The Vow Part Two’ turns to Nxivm on trial in docu-sequel

The bizarre and salacious nature of “The Vow,” with its intensely detailed look at the Nxivm cult, made the docuseries an understandable sensation, so much so that HBO came back for more. While “The Vow Part Two” gives viewers a front-row seat of the federal trial against founder Keith Raniere, it’s a more fragmented exercise that feels unduly stretched over six parts.