Lilly tracks a serial killer who eluded her months earlier. The chase begins after nine human skulls are found in the backyard of an abandoned house where a blind woman, whose killer was never found, was murdered in 1972. The woman's 12-year-old son witnessed the crime, and now is believed to be a mass murderer. Making the case more eerie is the fact that the killer knows intimate details about Lilly's life, which he tries to use against her.
Spoilers ahead. Coverage follows the scope labeled below.
Complete story — includes the ending
The discovery of nine human skulls leads the team back to serial killer George Marks, whom they were unable to incriminate months earlier. When the detectives decide to reinvestigate the murder of his mother, 33-year-old Simone Marks, in 1972, Marks emerges from hiding to face Det. Rush one-on-one. Song featured in the intro: " Sunshine on My Shoulders ", by John Denver. Song featured in the finale: " Behind Blue Eyes ", by The Who.