This is a great show. The friendship that goes back in the past, the suspense in every turn, the unexpected twists (I really liked the last one in the end of season one) and of course, the main plot, everything is planned fantastically.
First I wasn't even intrested in watching this show. But it really caught me there and and pulled me. It was really interesting to watch how the siblings find the keys and use them. I am waiting eagerly for season two to be released.