THE PROMISE is an intense, fast-paced and gripping Scandinavian thriller told in four parts. Nina's presence in her sister's grand villa has a strong impact on the whole family, and Nina and Klara's bond grows stronger. But the peace doesn't last long. Suddenly, Nina's past catches up with her in a dark alley, and she only escapes thanks to her quick reflexes and hard knuckles. Then, she gets a call from the institution where Gabriela is still imprisoned, and it's not good news ...