I finished Season 3 of Dark on Netflix.
Highly, highly, highly recommend. Especially for the Nerds. Word of warning though. Before you watch the 3rd season, it's best to spend 10 years at Uni studying Quantum Physics.
The first season is a little slow but sets it up as a show about families trying to find out what happened to their missing kids, and why one guy committed suicide.
Without giving too much away, it has a lot to do with time travel. The 1st season is a slow setup. The 2nd season is more in depth. The 3rd season is 10 levels of confusing. Fortunately it's all pretty much explained by the end of it but it's watching it just scrambles your brain. Not so much the science of it. That's fairly simplistic and often wrong. It's more the fact that there's so many characters operating across so many different times that just makes it really difficult to keep track of who is who. At times they would do a big twist reveal when someone would say, "my name is actually X?" with big dramatic music and I'd have to pause it and look up on imdb to remember who X was and stuff like that.
Still, very much worth a watch.