Detective Hole ending explained: Who was the killer and what happened to Waaler?

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*Warning – contains full spoilers for all nine episodes of Detective Hole.*

I’m so excited – all nine episodes of ‘Detective Hole’ are out now! It’s amazing to finally see Jo Nesbø’s brilliant detective brought to life by Tobias Santelmann. The series is a real rollercoaster – full of twists and turns that keep you guessing!

This season, inspired by Jo Nesbø’s novel The Devil’s Star, follows Harry as he investigates a serial killer in Oslo and simultaneously works to uncover the wrongdoing of his rival, Tom Waaler.

Ultimately, did Harry manage to defeat Waaler, and what became of him? Also, the story explores the identity of the serial killer who was frightening people in Oslo.

Read on for everything you need to know about the ending of Detective Hole season 1.

Detective Hole ending explained: Who was the killer?

The second-to-last episode of Detective Hole featured a surprising reveal: Lisbeth’s husband, Willy Barli, was actually the killer.

Harry discovered a crucial clue: seeds found under the fingernail of the severed finger belonged to a cafe Willy had visited on the day the finger was discovered. This led Harry to believe Willy was the one who killed Lisbeth, and that he’d placed the finger in his rectum after her death – contradicting Willy’s claim that she had done it herself.

He discovered his wife was having an affair with Martin Aminov – shockingly, it began during their honeymoon. Driven by rage, he decided to kill his wife, Lisbeth, and make it look like Aminov was responsible.

He killed three more people and staged the scenes to look like part of a ritual, hoping to shift the focus away from himself. If only Lisbeth had been the victim, he would have immediately been the main suspect, but the appearance of a serial killer created confusion and made it harder to pinpoint him.

Willy knew Aminov had once tried to sell the Barlis a star-shaped diamond, so he pretended to be interested in buying several of them as a way to locate Aminov.

Aminov would leave the diamonds in secret spots for Barli at prearranged times, allowing Barli to make sure Aminov didn’t have an alibi while he was committing the murders. Barli then recorded messages, disguising his voice, and left them at the crime scenes along with the diamonds, framing Aminov for the crimes.

Harry questioned Barli, and the killer nearly attacked him as well. Later, Harry discovered Barli had fallen onto a spike near his house – it looked like a jump, but the exact circumstances were unclear.

What happened to Tom Waaler?

In the last episode, Harry was closing in on the truth about Tom Waaler’s hidden past, so Waaler kidnapped Oleg, knowing how much Oleg meant to Harry.

Harry and Waaler planned a meeting, and when they met, Aminov was also there – he had the evidence to prove Waaler was guilty. Harry pretended Aminov had given him a key, then acted like he’d swallowed it, while handcuffing himself to Aminov. He then showed Waaler video footage of Waaler threatening them with a gun.

Okay, so things were getting tense. Waaler, clearly the one in charge, confidently said he had a plan and ordered Harry, Aminov, and Oleg into the elevator. What I found really interesting was that Harry had secretly hidden a gun in there, thinking he was prepared. But Waaler was one step ahead – he discovered the weapon and removed it. It immediately raised the stakes and made me wonder what Waaler was really up to.

A fight broke out, and Waaler attempted to force his way into the elevator as it rose. Aminov had managed to unlock his handcuffs using the actual key, so Harry secured that cuff to Waaler’s arm. As the elevator continued upwards, Waaler was pulled outside, but remained connected to Harry, resulting in his arm being torn off.

Despite being seriously wounded, Waaler climbed the stairs to reach Harry, and he died with Harry watching through a window.

In the episode’s final moments, Harry investigated Tom’s history and spoke with someone who knew him as a child. This person shared stories and rumors suggesting Tom had suffered abuse at the hands of his father, and ultimately killed him, staging it to look like an accidental death.

This added a tragic lens to everything we already knew about the complicated character.

Where did we leave Harry Hole?

In the last episode of the season, Police Deputy Chief Agnes Kittelsen asked Harry to rejoin the force. She explained that she needed his help to uncover and stop the remaining corrupt officers who were connected to Waaler.

At first, he hesitated, but after considering his work with Barli and talking to Kittelsen, he finally understood what really happened in the bank robbery and murder case that had troubled him for so long.

Beate discovered that Stine’s husband was the one who killed her. He hadn’t been considered a suspect before, as everyone believed the murder was connected to a bank robbery. But the robbery was actually a distraction – the real purpose was to kill Stine.

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He and Rakel were back together, and their relationship appeared to be improving.

The episode ended with a surprising reveal: Kittelsen was secretly working with Waaler. She’d been attempting to bring Harry into the fold, hoping he’d cover up Waaler’s activities and keep their network hidden.

She told a colleague she’d stay out of sight for a bit, but promised to return later, more determined than before.

Don’t miss Detective Hole! Add it to your watchlist on the TopMob: What to Watch app. Download the app today for daily TV recommendations and exclusive content.

Authors

James HibbsDrama Writer

James Hibbs writes about TV dramas for TopMob, covering shows on streaming services and traditional channels. Before becoming a writer, he worked in public relations, first at a business-to-business agency and then at the international production company Fremantle. He has a bachelor’s degree in English and Theatre Studies, as well as a journalism diploma.

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2026-03-26 17:37