The question is can a story about a gold coin be that interesting to hold the viewer in rapt attention all throughout the series? Yes. This is one instance where the viewer gets into a roller-coaster ride from Berlin to Vienna to Marseilles. The ride has enough traction that the viewer is willing to invest his time as the main protagonists go from one mishap to another.
The actors are competent in performing their roles credibly and naturally without hysteria. One can ask another pertinent question: can the relationship of Charly (Frederick Lau) and Joseph (Christoph Krutzler) happen in real life? I guess so if we consider their respective personalities.
The length of the episodes are just right, which means the pacing is ok. And the actors, coming as they do from different ethnic backgrounds, are able to pull off the scenes.
The last episode suggests another season is possible.
This series deserves your time and attention.