For those asking, yes the series will continue, not least because the Scands want it to after it was sold to Denmark. The actors say it was the hardest thing they have done, filming it back-to-back in Welsh and then English, but was well worth it.
Hinterland not only refers to the setting in the hills and sea coasts around Aberystwyth and Mid-Wales but to the plot lines where all the crimes have a backstory or hinterland of their own. It also refers to each individual character and not just the leads. There is no cardboard cut-out anywhere and all have motives and biases deeply rooted in the unknown, thus far, past which has made them who they are. I know a real-life person just like every character portrayed so far, got them spot on.
If you like shoot-em-up all-action fantasy this is not for you since scenes can be silent and slow, revealing emotion and thought processes but if you have any liking for fringe cultures such as Scandinavian noir then dig in. The tension is often unbearable not least the tension waiting for the next series.
