Last Night

Ayako Michaels, 16 and Female. Status: Alive.
Kylie Michaels, 17 and Female. Status: Deceased.

Wren is a 16 year-old girl trying to get over her sister's untimely death. 2 weeks after the funeral, a "research" group appears in Illinois, secretly digging up a he cemetery.
Revealing themselves as the Drowning Cult of the High Cross, seven kidnappings occur.

Who are these people and what do they want?
And why are they kidnapping teenagers?