One of the best films I've ever seen regarding repentance is the powerful 1998 film, "American History X." It tells the story of two brothers involved in the Neo-Nazi movement and their path toward redemption.
In this scene, older brother Derek begins the journey of repentance with the guidance of his former high school principal. For Derek, repentance is presented clearly as "metanoia" - a change in direction.
I want to note that this film does not paint repentance with rose colored glasses. It is difficult and painful - excruciating at times even - and it doesn't guarantee a happily ever after. In Derek's case, letting go of the violence in his life takes longer than letting go of the toxic beliefs that led him to violence in the first place. Yet, through it all, it is clear that Derek has made a true change of course that will set his life onto a new, more hopeful path.
There is a small amount of profanity in this clip so keep that in mind when watching.