Suicide or Sinister Plot

S1 E6: Police discover a car belonging to 19-year-old, Sarah Stern abandoned on a bridge, the keys still in the ignition, but she was nowhere to be found. Police initially suspected suicide, but why then would she withdraw thousands of dollars in cash just days before? Months go by without any sign of Sarah, until a tip from an ex-classmate reveals a truth so horrifying it could be a movie plot. Did Sarah end her own life, did she run away or was she the victim of a sinister plot?