To learn about an interesting real event
To learn about the historical period specifics:
Everybody smokes. Unsurprising how Philip Morris became what it is today.
It's just not a glass ceiling but apparent deliberate sexism.
It seems media is easily manipulated and controlled, or at best, we could say media has authority bias.
How difficult it was to solve a similar case (i.e. fingerprint 40s, DNA 50s)
To see a failure of being human, to explain everything in cause and effect even if it's happening randomly or correlated (i.e. age/location selection of victims)
To understand that people are always looking for easy money but there is no free lunch
To learn from the great dialogues which ease the tension between a wife and a husband in difficult times
To see a motivating example of grit
To enjoy a performance, Keira delivers as she always does in period dramas