When ex-detective-turned-teacher Jackie Ellis discovers one of her pupils dead, her estranged partner DS Bull returns to investigate.

Old accusations resurface as Jackie and Bull must put aside years of mistrust before the town's tensions ignite into violence

With the town turning on itself as long-buried secrets emerge, Jackie and Bull's fragile partnership is tested by a new discovery.

DNA evidence exposes a devastating truth, forcing Jackie and Bull to choose between protecting themselves or those they love.

Rising floodwater cuts Morfa Halen off from the world as another body is discovered, with Bull closing in on the truth behind an illegal operation at the heart of all three cases.

Jackie and Bull discover the horrifying truth behind the crimes that haunt Morfa. As Bull fights for his life and Jackie faces an unbearable choice, the storm reaches its peak.