A murder investigation is launched in the steel town of Port Talbot when the dead body of local businessman Stevie Rose is discovered in the town's marina. Ambitious policewoman Gina spies an opportunity to win promotion by helping to track down Stevie's murderer. Unbeknown to Gina, her brother Sam is befriended by a new neighbour with a favour to ask and he finds himself in possession of a gun.

Gina finally makes to make her way onto the investigation team, but the discovery of a second body poses the team more questions than answers. When Sam's employers get wind that someone has been stealing from the warehouse, a thorough search is conducted, and Sam fears he is to be found out – but when co-worker Cai is found to have a stolen child's toy in his locker, he is assumed to be the thief and is fired on the spot. Cai pressures Sam into compensating him for losing his job, and the pair decide to rob one of the company's vans full of expensive electrical equipment.

Carl begins to interrogate Stevie's family and friends in a bid to shed some light on his murder. Gina follows up on the reports of gunshots on Sam's estate and begins to suspect Rhys and Mel's involvement, unaware that Sam is struggling under the pressure of keeping his secret to himself. A loanshark with connections to Stevie is badly beaten by a gang of thugs. Layla is surprised when Patricia unexpectedly offers a reward for information relating to her husband's murder. Sam is devastated when his Nan's failing health finally gets the better of her.

Tired of Ray's constant niggling, Sam decides to get revenge by staging a second robbery, this time on his builder's yard. However, Sam's plans go disastrously wrong when Cai pulls the gun on a security guard who catches them in the act. Realising that the police are closing in, Cai decides to leave town, but not before trying to reclaim his half of the money from the van robbery. Gina is angry when she is sent home from work by Layla, and is surprised to be approached by Patricia, who tries to offer her money in return for undisclosed information on the case.

With Morgan missing, Caryn makes a police statement to Gina. Gina finds the killer’s address, but he’s moved on to a new target: Jeff.

While staying at a hotel Sam and Ela take advantage of another guest with heartbreaking consequences for Sam. Gina searches for more information about her father's death.

Knowing he could be the next victim, Jeff’s son, Richie, offers to let the police use him as bait to draw out the murderer. Sam discovers something shocking about Caryn.

Gina comes across information that casts fresh light on her father's death and the discovery leads to an honest conversation with Linda about the past. Sam meets a woman called Ela who turns his life upside down.

Gina starts to suspect Sam and the truth comes out about the gun. Gina is forced to make a difficult decision and a meeting with Douglas Rose floors her

Gina is horrified to learn Sam is in danger. The truth about Stevie Rose's murder is revealed. Gina discovers something in Ray and Linda's house that leads Sam to remember what exactly happened to his father.

Dai is rattled when his bike shop is broken into, but he won’t tell Sam what’s wrong. Gina and Luke investigate reports of a gunshot heard near one of Jeff’s businesses.

With the discovery of another body, the police connect the victims to a rugby club whose members were accused of rape years ago. Sam gets closer to his new boss, Dai.

When Gina discovers a body on the beach, the victim’s boyfriend accuses a local businessman. Gina is distracted from the investigation by Sam’s return home from prison.

After his argument with Gina, Sam stays with his mother but still gets caught up in the feud between his caseworker, Caryn, and her husband, DI Morgan Riley-Gina’s boss.