Mervin is about to fly home but finds himself at the centre of a murder investigation when a body is discovered in his shack. As Mervin professes his innocence, the team can't work out how the victim ended up inside a locked building with no sign of forced entry. The woman's identity remains elusive until they discover she was volunteering at a local turtle conservation charity, and suspicion falls on her colleagues. Meanwhile, Selwyn grapples with his most difficult decision yet when he delivers some personal news to Mervin that turns everything on its head.

Mervin reopens his mother's case and uncovers the prime suspect in her murder. But even though everything points back to this suspicious figure, they can't work out how foul play was involved. By all accounts, Dorna took a boat out in a storm of her own volition and drowned at sea. Just as the team starts making headway in the case, Sterling pulls rank and throws a spanner in the works. Can a world-weary Selwyn help them before it's too late?

And old wounds are reopened as Mervin is forced to confront his past. But will he finally get the answers he's looking for?

Mervin and the team explore the world of online dating when a local man is shot dead at his villa. He was waiting for a woman he'd met on an app when their video call was interrupted by an intruder. But Mervin's puzzled by the presence of a bullet in the victim's hand: why would the killer have put it there? The team must uncover lies, deceit and the lengths people go to for love in order to crack this case.

Meanwhile, a new colleague makes an impression for all the wrong reasons, and Mervin's like a dog with a bone as he reopens his mother's case, catching the attention of a suspicious figure...

Mervin begrudgingly embraces island life and agrees to watch a local women's football game with the team. But half-time sees a bloody discovery when the star player is found dead in the locker rooms with a fatal bullet wound. The team are left perplexed when it becomes clear that the only way to access the changing rooms is via the pitch - and no-one in the crowd saw anything. So, how did the killer slip through the net? As Mervin feels the pressure from Selwyn over a murder that took place right under their noses, Naomi is at a crossroads when someone from her past turns up on the island.

A distillery owner is poisoned during a group tasting of his premium rum. But the case is shrouded in mystery when it's revealed all the guests drank from the same bottle. So, how could the killer ensure only the victim would wind up dead? As Seb's unorthodox methods prove useful to the investigation, Mervin learns an important lesson in slowing down. The team must dig deep into the past, uncovering secrets that our suspects have gone to great lengths to bury, in order to get to the bottom of this case.

At the launch of her highly anticipated skincare product, a wellness business owner suddenly dies from an allergic reaction. But Mervin quickly deduces her death to be suspicious when, despite the presence of peanuts in her throat, the victim didn't eat or drink anything. Meanwhile, Darlene struggles to train up newbie officer Seb Rose as they investigate an obscure party drug that's doing the rounds on the island. And tensions run high as Selwyn battles devastating news, while Mervin begins to doubt his own instincts when he uncovers compelling evidence in his mother's case.

Mervin and the team have quite the mystery on their hands when a game show contestant is stabbed during filming of the series's grand finale. In a baffling turn of events, the victim is murdered in midair whilst hurtling down a zip line. As various members of the TV crew come under suspicion, Mervin surprises his colleagues by signing a contract to prolong his stay on Saint Marie. But he and Selwyn butt heads when it becomes clear Mervin has an ulterior motive for extending his visit. And it turns out that Selwyn has secrets of his own...

The team looks forward to welcoming a new recruit into their midst, whilst Mervin can't wait to get off the island. But before he catches his flight, Mervin becomes embroiled in the murder of a young man who's found in a ravine. The case becomes more compelling when they find the victim has left them a mysterious message.