The Breakthrough (2025) – Season 1 Episode 4 Recap, Review & Ending Explained

Episode 4

Episode 4 of The Breakthrough begins with Per needing more people in the database to confirm the killer’s bloodline. Desperate, the police squad and their acquaintances agree to get swabbed.

A reporter snoops around and Stina wants to get ahead of him. She calls in her favour for the exclusive – an interview with Per. He insists there is no time but agrees if she swabs which she does. Unfortunately, Klara runs away again. John gives in and tells Per to go to his daughter and work from home which he does.

How is Per able to find the killer?

The coach finally speaks up and feels guilty for being so late. He explains that he just didn’t want the killer to be Ante. Francy recalls questioning Ante and how he refused to get swabbed which was normal back then as it was a voluntary request. He also had an assault charge three years prior and lived near the crime scene. It is enough for the cops to arrest him.

Meanwhile, Per narrows the region down further to Algbosatter but pauses his search as John tells him about Ante. However, Ante is not a match. The search resumes as Francy sends the new swabs to Per. He is shocked to find the strongest match with Stina. He rechecks the family tree he has constructed again and again to ensure he is right. The match that comes up every time is – Stina’s twin cousins, David and Stefan Nilsson. 

Confident, John requests an arrest warrant. While Stefan has a job and a family, David is mentally unstable and lives in isolation. The judge agrees to the warrant and a tactical unit.

How does everyone react to the arrest?

Of course, Stina finds out about the tactical unit. She insists on intel and threatens to talk about the case online. Not wanting David to get a heads-up, John tells her she is the missing piece.

That evening, Per and John separately show up at the crime scene. Per is worried he may be wrong and John tells him not to worry.

It is past 6 am and the squad is one edge. David’s arrest is smooth and they do a swab. While they wait for the results, the cops recall how David had refused to do a swab back in 2004. It is a match and everyone is relieved. During the interrogation, David confesses that he killed Adnan and Gunilla as the voice in his head told him to kill two people to find peace. The cops gather that he is a recluse and he only ever spoke to his brother.

The cops alert Stefan who tears up as he is shocked. John tells Gunilla’s husband who reveals he dreamt of her that same morning. Next, Adnan’s family is informed. Saad thanks John for keeping his promise and gives him Adnan’s watch. They introduce their youngest daughter, Gunilla.

Per wonders what happens next and John decides to patch up with his son. He apologises and wishes to be in his life. Henry agrees, congratulating him on the case which has John delighted.

At the end of The Breakthrough Episode 4, we see that Per’s lectures are a hit. Klara helps him and one day, Stina visits. She shares a photo of her and David and wonders what went wrong with him. She wants to write a book on genealogy and Per agrees to join her.

Is The Breakthrough based on a true story?

Yes, The Breakthrough aka Genombrottet is based on a true story. It is adapted from the non-fiction book, ‘Genombrottet’ which is written by Anna Bodin and Peter Sjolund, the real-life counterparts of Stina and Per.

In October 2004, Linkoping, Daniel Nyqvist kills Mohamed Ammouri and Anna-Lena Svensson with a knife. His blood is on the knife and he abandons his beanie. The cops conduct over 5000 DNA tests but none of them matches the killer.

In 2010, the first composite sketch is revealed followed by a second sketch in 2018 based on the killer’s DNA profile.

Two years after the arrest of the Golden State Killer, in 2020, the cops have a breakthrough as they enlist Sjolund who uses genealogy mapping to trace the killer’s DNA and find his bloodline. Initially, Daniel’s brother is arrested before he is let go. Daniel is confirmed to be the killer after his DNA matches the hair found in the beanie. He confesses and gives the same reason as David in the show.

He has been charged with murder on two accounts. He is sentenced to psychiatric care and monetary settlement to Ammouri’s family and the state. Svensson’s family refused any settlement while the Ammouris’ youngest daughter is indeed named after the second victim out of gratitude.

The Episode Review

The Breakthrough Episode 4 is quite anticlimactic when it comes to the conclusion of the case. Sure, there is the emotional aftermath with the bereaved families which is the only positive part of the episode. But the finale is too short, too crisp and quick.

While the previous episode lingers too much on the genealogical technique, this one doesn’t linger enough on the arrest. It is not a satisfying reveal. We have no connection to the culprit and by the time the coach confesses, we know Ante is a red herring. Had the reveal been more dramatic, the finale would have held more weight. 

It is also surprising how poorly they have characterized Stina’s role when she is clearly an important catalyst in the show and in the real investigation. Instead, they portray her as this annoying reporter with no integrity who is only after the latest scoop and may even jeopardise a case for the sake of a story. A wasted potential, all in all.