When a teenager and her sister are the sole survivors of the gruesome murder of four members of one family in a quiet suburban neighborhood, Grissom and his entire team investigate the crime. What initially looks like a bizarre cult murder becomes more disturbing when they discover the motive behind the massacre.

When Nick, Greg and Hodges take Henry to celebrate his birthday at a biker bar, they uncover a double homicide and find several suspects still at the bar who may be the murderers.