If they stick to the same format the first two seasons are basically individual mini-series on their own, set years apart. A few characters cross over between them or are related to people from the other. Season 1 is more modern and season 2 is a flashback to something mentioned in season 1.
Also be warned that there is usually one 'supernatural' type thing on these that comes out of nowhere just to help remind people that it is fiction even though they stick to the based on real events type storytelling like the movie. Not trying to spoil anything for you it can just catch people off guard when you're into the story. Looking forward to this coming back, really enjoyed the first two seasons.
