Who is Goliath in BBC One's Bloodlands?

When local businessman Pat Keenan goes missing and Goliath's calling card is found at the crime scene, police assume the serial killer has struck again – but we've since learned that the kidnapping was made to look like Goliath's work to force the police to reopen the assassin's case.

So who kidnapped Pat Keenan? And who actually is Goliath? With lots of information to process, major plot twists to think about and theories to dissect, we've made a shortlist of the most likely candidates for Goliath – from the obvious suspects to a few surprising guesses.

Here's everything we know so far about the identity of Goliath in Bloodlands.

Jackie Twomey

So far, all clues are pointing towards Detective Chief Superintendent Jackie Twomey (Lorcan Cranitch) being serial killer Goliath.

From episode one, the super suspicious Jackie repeatedly told Tom to stop investigating leads relating to Goliath and to focus on finding Pat Keenan, even though the two cases were undoubtedly linked. He even removed Tom's boss, Superintendent McAllister, from the case after she told him to look into any Goliath connections and put himself in charge instead.

While alarm bells were already ringing at this point, we find out that Jackie failed to tell Tom about a major lead relating to the burial place of Goliath's victims, provided by David Cory's brother Adam 20 years ago. When he reveals his prior knowledge to a shocked Tom, he then tries to shut down the dig and tells him the lead is utter rubbish – however, shortly afterwards, it turns out there were three bodies found on the island.

Then in episode two, we watch as a sketchy-acting Twomey heads to his caravan, retrieves a secret burner phone and meets up with Siobhan Harkin – the widow of IRA quartermaster Joe Harkin who was murdered by Goliath. During their clandestine meeting, he tells her that they "need to be careful".

In episode three, we then learn that Jackie is a suspect in Adam Cory's murder (although we know Tom was the murderer in that case) and the Goliath case, as he is one of three officers within the department who was active in 1998. Niamh, Tom and Birdy discover that most of Jackie's police file has been redacted, potentially by the intelligence services, and that he had been unofficially running Joe Harkin – one of Goliath's victims – as an IRA source and communicating sensitive information via his allocated police post box. Jackie later confirms that it was him doing this when he meets up with Siobhan Harkin again and warns her that she's in danger as the police have figured out it was him passing information about Joe Harkin and that they'll discover she was helping him.

When Tom plants Goliath's calling card in his caravan, Jackie is arrested for Adam's murder – but is Jackie really Goliath. This may be too much of a give away and with one episode left, Goliath is likely to be someone we don't expect at all.

It's also likely that Jackie's file was redacted as he was involved in an intelligence mission – perhaps involving Siobhan Harkin. He may have been working undercover to uncover Joe Harkin's IRA links with the help of his wife and perhaps that is why he's been so cagey when revisiting the Goliath case?

Dinger

Tonight's episode of Bloodlands – episode three – floated the idea that forensic detective Dinger (Michael Smiley) could be the person behind Goliath, considering he was one of three officers within the department who was active in 1998, knew about the Goliath case and was given the tip about Frankie MacFealie (Adam Cory's alias).

While we obviously know Dinger didn't kill Adam, we can't rule him out as Goliath just yet. Goliath is someone within the police who has the ability to remove important case files and contaminate evidence – and Dingers fits that character description. He was one of the first people at the island crime scene and would have known how to remove all evidence of his involvement.

He also told Niamh in episode two that the bodies in the island grave belonged to Joe Harkin, David Cory and Father Simon Quinlan, hinted at Jackie Twomey being the person behind Goliath and suggested that Tom's wife Emma may have engineered her own disappearance, being in 14 Intelligence Company, the Special Reconnaissance Unit. Was he perhaps trying to throw Niamh off of his scent?

Tom Brannick

Drawing the conclusion that Tom is actually Goliath may seem a bit ridiculous, but after the dramatic ending of episode two, Tom does start took look a bit suspicious.

In the last five minutes of the episode, we watch as Adam Cory accuses Tom of being Goliath, pointing to his wife's affair with David Cory as a motive for Tom to kill David. Instead of diffusing the situation, Tom decides to shoot Adam dead in what appears to be a rather impulsive, stupid move.

While you could say Tom killed Adam in fury, having just learnt about his wife's secret affair, taking Adam out to the island, where Goliath's victims were buried, by himself with no other police officers does look a bit shady.

Meanwhile, in episode three, he appears to be rather un-phased by the cold-blooded murder he committed and ceases upon the opportunity to frame Pat Keenan for Adam Cory's murder and Goliath's identity when he instructs Tori to plant evidence in his caravan. Could all of this have been done to stop him being identified as Goliath? Was Adam right to accuse Tom of killing his brother and his wife Emma out of anger?

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Siobhan Harkin

In episode two, we meet Siobhan Harkin (Cara Kelly) – the widow of Joe Harkin, an IRA quartermaster who was murdered by Goliath.

While it seems unlikely that Siobhan would be Goliath, the person responsible for murdering her husband, we know she's definitely involved in something shady with Jackie Twomey after the two secretly meet up and vow to "be careful".

She's also immediately suspected by Pat Keenan as being the person behind his kidnapping, with the haulage businessman sending a member of his criminal gang to kill Siobhan – a job he failed to do after Tom and Niamh intervened in time. While she claims to have an alibi at the time of Keenan's disappearance, she reveals Keenan thinks her husband owed him money when in actual fact it was Keenan who owed Joe money.

With her connections to Jackie and her husband's potential debt, could Siobhan be the criminal mastermind behind Goliath?

One particular spanner in the works in this theory would be the suggestion in episode two that Goliath wasn't behind the Pat Keenan disappearance at all. At the end of the episode, Adam Cory confirmed he knew who'd kidnapped Keenan, with Tom suggesting he'd made the kidnapping look as though Goliath was responsible so the police would reopen the case and find out what happened to his brother.

This would mean that Siobhan could have been involved in Pat Keenan's kidnapping without necessarily being Goliath.

In episode three, we find out that she'd been working with Jackie Twomey to run her husband Joe as an IRA source and pass on secret information to someone unknown. Could she have done this to let Goliath know that her husband had links to the IRA in the hope that he would be killed?

Hopefully, the situation will become clearer in the show's finale next week.

Superintendent McAllister

In episode one, we watched as Jackie Twomey removed the seemingly enthusiastic Superintendent McAllister (Flora Montgomery) from the Pat Keenan case after she told Tom to pull all the resources he needed to track down Goliath.

Could her full support be a strategy to distract Tom and his team from suspecting her while Jackie, an accomplice in this theory, made plans to move her out of the spotlight? She'd be the suspect viewers would least expect due to her little air time, so she's definitely a possibility when it comes to Goliath's identity.

Emma Brannick

While episode one led viewers to believe Emma Brannick, Tom's British Army Intelligence wife, had been kidnapped and murdered by Goliath in 1998, information comes to light in tonight's episode that hints this might not be the case.

We find out that she isn't among the bodies found on the island and that, according to Adam Cory, she was having an affair with his brother David, who she had given her cherished owl pendant to.

Meanwhile, crime scene investigator Dinger suggests that Emma may have engineered her own disappearance since she was a spook, saying: "If anyone could, she could."

Is it possible that Emma began an affair with David as part of her undercover investigation, committed the Goliath murders and made sure her owl pendant was on Adam's body so that police would believe she had been murdered while she fled the country? It seems like a far-fetched theory but with the twist and turns we've seen already in Bloodlands, you can't rule it out.

Bloodlands continues on Sundays at 9pm on BBC One. If you’re looking for something to watch tonight, check out our TV Guide or check out our Drama hub for all the latest news.