I was watching once a week through the first 3 or 4 episodes and then the plot accelerated so I binged.
Very emotional ending.
Since it had great ratings in the UK, it seems there would be a S3 but how many missing children stories can they do?
The other long-run European crime dramas, like the The Bridge as well as The Missing, took a long time to gestate these single-crime plots. Not easy to hold attention over 8-12 episodes on essentially one story.
But also may be difficult to do another one because of the subject matter. Most missing children cases seemed to either be solved quickly or doesn't get solved at all, as happened in S1 despite the maniacal persistence of the father and Baptiste.
And it's usually not some conspiracy involving people helping the abductor, as was suggested in S1. It's usually a family member, like a parent who lost out on a custody case, just taking the child and running away.