Mike launches right back into his old investigation when Gretchen is found dead and all the clues point to the RRK: the Russian River Killer.

A man from Mike's troubled past resurfaces and Leo reveals more of himself to a student than he's comfortable with.

Just as another near victim is discovered, Mike and Cyd learn about a missing person from 26 years ago.

A father and son hunting trip takes an interesting turn, while further doubts are cast over whether Gretchen was an RRK victim.

The RRK meets his next victim, while Cyd faces a tense standoff.

The RRK meets his next victim, while Cyd faces a tense standoff.

A victim's body goes missing.

Leo receives an interesting offer from a neighbour. Meanwhile, Paxton and Sam discover a shrine to the murderer's work.

The RRK seems to have gotten away with murder - will the killer's true identity be revealed before it's too late?