The Jetty Ending Explained: What Happened on the Night Amy Disappeared

Warning: contains The Jetty finale spoilers.

Midway through The Jetty’s final episode, there are multiple potential suspects in the Amy Knightly case. Chief of all is DC Ember Manning’s dead husband Malachy ‘Mack’ Granger, the man who was secretly having a sexual relationship with underage Amy at the time she disappeared. There’s also Mack’s recently revealed half-brother Joe – now a convict with a violent past – who had threatened Amy and blackmailed Mack about his statutory rape of her.

You might also suspect Amy’s lesbian schoolfriend Caitlin, whom Amy manipulated and betrayed, and who left town years ago. And for that matter, there are also Caitlin’s homophobic parents, who hated their daughter’s new friend and denied Caitlin’s true identity. So many possibilities.

One suspect on nobody’s radar though, was DC Manning herself. And that’s who turned out to have been Amy’s inadvertent killer.

Who Killed Amy Knightly?

The cop investigating a murder turning out to be the very killer that they’re hunting is a lurid twist more fitting of pulp crime fiction than The Jetty’s realistic setting. Nonetheless, that’s what happened here. Amy Knightly died after hitting her head on a rock when she fell down a roadside embankment, having been hit by a car. Driving that car, illegally and high on drugs, was 17-year-old Ember Manning.

Amy died on the night of Ember’s 17^th birthday. Mack had lied to Ember that he couldn’t come to her birthday at the local pub because he had a factory shift, but really he was breaking up with Amy at the boathouse. They fought, as witnessed by Mack’s half-brother Joe, who took Mack’s car and left them there. Mack messaged Arj and Ember to come and pick him up, and – high on Rohypnol – they went to get him. Ember was behind the wheel, despite not having a driving licence, and she accidentally knocked over Amy, who’d been walking on the side of the road. Mack told Ember that she’d only hit a log and to keep driving. Later, to protect Ember, Mack convinced Arj that he had been the one driving, and the pair of them retrieved Amy’s body and buried it under the boathouse basement.

Who Killed Podcaster Riz?

That was David “Arj” Argent, played by Matthew McNulty. Because the boathouse had been sold to a new owner and was being renovated, Arj feared the discovery of Amy’s body,  which he and Mack had buried in the basement 17 years ago. To cover their tracks, Arj dug up Amy’s remains and set fire to the boathouse, but he accidentally left a piece of Amy’s skeleton behind.

The private investigator that podcaster Riz had hired to get information on Amy’s disappearance discovered the bone fragment and photographed it, before DC Manning confiscated his bag of evidence. Arj knew that Riz had the photograph and so he stole her laptop to delete it. Riz tracked her laptop to the boathouse (the sound Ember heard on Riz’s audio recording of her murder was the rotating radar antenna on a nearby boat, which is how she realised that Arj had killed Riz), and Arj strangled her to death and threw her body in the lake.

Why Did Ember Lie to the Police?

Because, as adult Caitlin (now academic Kit Owens) told her, there’s a difference between truth and justice. The truth of Amy’s death was that teenage Ember was responsible for knocking her off the road, but would Ember confessing to that and losing her daughter and job, represent justice? No, she decided.

Arj had spent the last 17 years believing himself to have been Amy’s killer and not come forward to give her parents closure on her disappearance. When Ember discovered that she was the one driving that night, she immediately resolved to own up and told Arj that they needed to hand themselves in. Arj, however, wanted to be with Ember and for them to continue to cover up their role in Amy’s death. When Ember refused him and insisted that they tell the truth, he strangled her into unconsciousness, poured petrol on the jetty and attempted to burn them both to death. It was only Ember waking up and jumping into the water that saved her life.

Knowing that Arj had murdered Riz, attempted to murder her, and had lied about what happened to Amy for 17 years, Ember considered it justice that he be blamed for Amy’s death and she be left to continue her work protecting local girls like Miranda and Amy from underage sexual abuse.

Why Did Amy Lie to Caitlin About Having Sex With Mack?

Mack’s half-brother Joe was blackmailing him about his illegal sexual relationship with underage Amy. Joe said he would report Mack to the police, and took the photograph of Amy sitting on Mack’s lap as evidence to support his claim. To stop him from going to the police, Mack made an unsavoury deal with Joe – Amy would groom another underage girl for Joe to have sex with in exchange for him not reporting Mack and Amy’s illegal relationship.

Convinced to do so by Mack, Amy recruited Caitlin and groomed her. She recognised Amy’s lesbian attraction to her and used it to manipulate Caitlin into having sex with Joe, to protect Mack from the police. She told Caitlin that she wanted the two of them to lose their virginities to men at the same time, forever connecting them. In reality, Amy and Mack’s sexual relationship had been ongoing for some time before the night that Caitlin lost her virginity. After having sex with underage Caitlin, Joe would, depending on his age, either be equally culpable or be placated enough not to report Mack.

In the middle of all the lies and grooming, Amy and ‘Kitty’ did share a My Summer of Love-style romance in which Caitlin loved Amy, but was lied to and betrayed by her.

Where Was Everybody Left at the End?

Caitlin, now Kit, reunited with her parents and visited her dementia-suffering mother who, we’re led to believe, was also gay or bisexual and had repressed her own sexuality due to shame and fear. Now out and living as her true self, Caitlin had overcome her own internalised shame and transcended her mother’s sad story.

Ember told her mother, Hannah and Kit the truth about her role in Amy’s death, but chose to let Arj take the blame for driving the car that hit Amy. Ember stayed with the police and promised Miranda that she would pursue the men who had paid to have underage sex with her, to make a better world for Miranda’s baby daughter. She ended the series scattering Mack’s ashes with her mother and daughter in a multi-generational show of female endurance.

The Jetty is available to stream now on BBC iPlayer.