Huge plothole

The understanding of that may be beyond the scope of this board (though due to their early connectivity, in terms of the murders, they did seem to end up being handled by the same team).

But the place to truly find answers and robust discussion is www.guardian.co.uk, where you can search for the excellent weekly Modus recap reviews and the posts by viewers written below the news article every week.

They have a lot of useful insight to explain the more mysterious plot points.

I've learned a lot reading those!

As my other thread suggests, the Guardian newspaper does "Modus" better than the original show does!

It's two cities, Stockholm and Uppsala.

But I don't see it as a massive plot hole. Ingvar Nyman is from the rikspolisstyrelsen (that's how he introduced himself to Hammar) — the central coördinating body* so when Bishop Elizabeth is murdered local cop Hakim Hammar is there first but it's entirely reasonable that Nyman should be called in to what is obviously going to be a high profile case.

Thereafter they have a spate of murders and begin to make the connections. Recall also that Sweden is a country of less than 10 million people, not that much larger a population than London or New York.

Then Nyman is not the first investigating officer on the Hawre case, Sundberg is. Nyman gets involved because of the placing of the body outside Ståhl's office making a connection with his existing investigation.

Taking it all together I don't really see a hole, and certainly not a huge one.

[ * I'm making the assumption that this was written before last year's reorganisation that united the 21 district police forces into a single authority, the Polismyndigheten. ]