Who killed Eadie Tulloch? 5 major theories from Shetland Series 10

Spoiler warning: This article dives deep into early Episode 1–3 of Shetland S10. If you haven’t watched yet — step away!

The set-up

In the chilling premiere of Shetland Season 10, the idyllic — but isolated — hamlet of Lunniswick becomes the centre of a dark mystery. The body of retired social worker Eadie Tulloch is discovered behind a shed by a neighbour. She had been strangled and then left out in the elements for days. There was no sign of a forced entry or struggle in the house; the scene suggested she was dragged outside. tvguide.co.uk+2Radio Times+2

Add to that: Eadie reportedly had around £400,000 in the bank, yet lived like a recluse, depending on neighbours’ charity. tvguide.co.uk+2Entertainment Daily+2

As detectives dig in, a tangled web of secrets emerges — everyone seems to have a motive or something to hide. tvguide.co.uk+2Yahoo News UK+2

Below — five of the strongest theories that detectives and fans are exploring.

Theory 1: David Powell — the troubled neighbour

• David is a young neighbour recently released from prison for house-breaking; his mother Gina is fiercely protective and refuses to divulge details. tvguide.co.uk+2Shetland News+2

• Police suspect he might have visited Eadie’s house — possibly “tiling work” turned into a burglary cover. His room was found to contain some of Eadie’s jewellery shortly before her death. tvguide.co.uk+1

• On the face of it, David looks like a strong suspect — a known offender, recently out of jail, with access to the victim’s home.

But — his defence is that Eadie gave him the jewellery as payment for tiling; and there was no sign of forced entry, suggesting a more intimate or trusted kind of access. tvguide.co.uk+1

Thus, while David is one of the first suspects, many consider him less likely — especially if the motive was more personal or predatory than opportunistic. Yahoo News UK+1

Theory 2: Family betrayal — Ed Tulloch, her estranged son

• Eadie and Ed, her surviving son, were estranged: they “hadn’t spoken in years.” tvguide.co.uk+1

• Ed runs a pub nearby and claimed not to know about the large sum of money in Eadie’s account — his claim raises suspicion, because that stash is now a major motive. Radio Times+2Entertainment Daily+2

• Also, there’s growing emotional connection between Ed and DI Ruth Calder — a subplot with high dramatic stakes. Entertainment Daily+1

Given all that, some viewers suspect Ed might have had incentive — financial or emotional — to silence Eadie.

But so far, there’s no direct forensic evidence pointing at him (no DNA, no rope fibres, no witness placing him at the scene). Entertainment Daily+1

Theory 3: Arthur Mair — old friend, secret lover, suspicious visitor

• Eadie and Arthur had had an affair in the past. More shockingly — Arthur admits he visited Eadie the night she died, bringing food and whisky. Entertainment Daily+2Yahoo News UK+2

• The autopsy showed Eadie had a “skinful” of whisky in her system — odd, given she was elderly and reportedly didn’t drink. Entertainment Daily+1

• It’s possible that Arthur — perhaps following through on the affair — took advantage of her vulnerability. Especially if the motive ran deeper than just passion (money? secret guilt?).

However, by the end of Episode 2, detectives let Arthur go — he claimed to have left her fine and returned home to his wife and family. Entertainment Daily+1

At this stage, his behaviour seems unsettling — but not conclusively murderous.

Theory 4: Stevie Shannon (or her sister Amy Shannon) — someone from Eadie’s past with a grudge

• When Eadie was working in social services, she had removed Stevie and Amy from their birth mother. The sisters were split apart — a traumatic move. Amy later sued social services. Entertainment Daily+2Yahoo News UK+2

• Stevie has a troubling history, according to the subplot — rumours that she manipulated other children in foster homes and encouraged them to run away. Entertainment Daily+1

• In Episode 3, the police learn that Stevie visited Eadie’s house the night she died — she took a taxi to Lunniswick and admitted she “just stood outside… watching her through the window.” She avoided speaking to the police earlier because she feared they’d suspect her. Entertainment Daily+2Yahoo News UK+2

Given this, it’s plausible that Stevie (or with Amy’s influence) harboured long-term resentment toward Eadie — making this a revenge-killing.

Still — there’s no evidence any social-work grudges escalated to murder, and no proof of forced entry or struggle. It feels like a stretch… but in Shetland, darkness sometimes lurks where you least expect it.

 Theory 5: A darker secret — corruption, stolen money, hidden crimes (involving Robert Tulloch & Billy McCabe)

Here’s where the case gets truly complex:

• Eadie’s bank account contains around £400,000 — a huge sum for a retired social worker living off neighbours’ charity. tvguide.co.uk+2Radio Times+2

• Investigation reveals those deposits were made over 12 years by her late husband Robert Tulloch. They stopped when he retired. The couple had no other significant income sources. Entertainment Daily+2Radio Times+2

• That raises the possibility Robert was involved in corruption — possibly illegal money, bribes or shady dealings. Radio Times+1

• Then there’s Sgt Billy McCabe — a long-standing, trusted police officer. He was once mentored by Robert, and the two families are intertwined. Billy has been found to hold the missing bank statements that could shed light on that money trail. Entertainment Daily+2Yahoo News UK+2

• If those deposits formed part of a criminal enterprise, it’s possible Eadie was a liability — maybe she planned to expose it, or someone feared she might. Murdering her and hiding the body could be the most brutal way to bury the past.

This theory turns the story into a sprawling crime thriller — corruption, betrayal, and a cover-up that could shake the very foundations of trust in the island’s community.