At the beginning of the film we already know that something bad has happened. The story is told through the narration of one of the main characters, while he is having flashbacks of what leaded to some tragic events.

Walter Neff is an insurance salesman that falls in love with a married woman called Phyllis Dietrichson. She completely blinded him with promisses and told him that she had an unhappy marriage and she just wanted to be happy with him. Then she made up a plan for them can be together, they just had to make the husband sign some life insurance papers and do a scheme to kill him later.
A story of greed and betrayal about a man who was deceived because he wanted to be loved and happy.

Overall, great story, great direction, great performances and great cinematography, all together turned it into a fantastic film.

Double Indemnity is definitely one of the best film-noir ever!