For weeks, we have watched each episode of BBC One’s Dublin Murders with bated breath, always with one question on our lips: who killed Katy Devlin? And tonight’s episode – the show’s seventh and penultimate chapter – finally revealed the shocking truth.

Or did it? As ever, the show left us with plenty of unanswered questions as we watched Cassie Maddox groggily awaken from her cocktail of Ketamine and Rohypnol, Rob Reilly violently attack Shane Waters, Rafe unveiled as the reluctant father of Lexie (RIP)’s baby, and plenty more besides.

Here, Stylist’s digital editor Kayleigh Dray does her best to unravel everything before tomorrow night’s explosive finale. You’re welcome.

Did Damien Donnelly actually murder Katy Devlin?

All it took was a stale biscuit to kick things into motion. As Rob Reilly thoughtfully munched on his choccy digestive at the archaeological dig, he suddenly remembered that Katy Devlin’s stomach had been empty at her autopsy… save the remains of (you guessed it) a chocolate biscuit. Shocker.

“Whose biscuits are these?” he asked frantically, only to learn that the tin belonged to Damien Donnelly. As in, yes, the very same Damien Donnelly who discovered Katy’s body and cried all over it (handy for explaining away all that DNA, we guess) all those weeks ago.

It isn’t long before Rob is storming the house where Damien lives with his bedridden mother, desperate to find something, anything that will implicate the young man in Katy’s murder.

“Her clothes had been washed and dried,” he reminded his forensics team. “She’d been kept somewhere.”

Using a UV Black Light to examine for crime scene evidence, Rob soon finds what he’s looking for: bloody handprints all over the garage door, where a desperate Katy had tried her very hardest to escape. Tragically, as we all know, she never did.

It’s at this moment that Damien returns home, well and truly ready to face the music… but something seems amiss. Could he really have committed this terrible crime? And, if so, did he act alone?

With one whole episode to go, we highly doubt that this case is wrapped up and finished. In fact, we strongly suspect that Damien may reveal himself to have been working as part of a team, either with one or several others. We guess we will have to wait until tomorrow evening to find out for sure, though.

But who could he have been working with?

Well, anyone really. Shane Waters told Katy Devlin’s dad that he’s to blame for Adam/Rob’s traumatic night in the woods all those years ago, which is interesting – and Terry Andrews is the one who left those threatening messages on the Devlins’ answerphone.

Then there’s Katy’s creepy sisters, creepy mum, creepy dance teacher. And let’s not forget those creepy cultists who like to serve the old gods wine and nudity of an evening, too.

Is Rob/Adam a killer?

Rob is still high on our list of suspects, if not for Katy’s murder than for the disappearance of Peter and Jamie back in 1985. After all, this is the same guy that violently beat Shane Waters to a bloodied pulp when the former recognised him as Adam. And this is the same guy who suffers extreme amnesia about the events of that fateful night… and seemingly has selective memory around his friendship, too.

“You used to worship those kids, but they were vicious to you,” his mother tells him, after a dramatic sleepwalking incident (more on that later). “I didn’t like them because they were bad kids.”

Rob’s mam goes on to remind him that Jamie and Peter used to leave him in the woods alone, and that he would come home alone, crying, on a regular basis.

“You’re remembering it all wrong,” she insists. “You’re trapped in it.”

Hmm. Maybe Adam/Rob (or his mum) finally snapped after one bullying incident too many, eh?

What does Rob want to tell Cassie?

Rob leaves a very interesting message on Cassie’s answerphone.

“Come back,” he says. “There’s something I want to tell you.”

A confession of some sorts, surely… but a confession of love, or a confession to murder? Too bad she hurled her phone across the room in a wild rage rather than calling him back, eh?

Dublin Murders episode 7 recap: [SPOILER] killed Katy Devlin – or so they’d have you believe