Season 1 of Fallen premiered on December 25, 2023.

The recently widowed police officer Iris Broman travels from Stockholm to Ystad in southern Sweden, where she will reside in her sister's home while taking up the new position of leading the cold case unit in Malmö. A body is found and there is an unsolved murder from over 10 years ago, and Broman also has to deal with her personal trauma and complex relationship with her sister, Kattis. Kattis is married to a French man and her children are bilingual, while Broman has no children and no desire to have any.