In order to progress through heaven’s gates,? ghosts must pay penance by returning to earth and helping the people they hurt.

What you have here is world-building.

You don't have a lead character, your lead character doesn't have a specific goal, and what is standing in the way of the lead character's goal?

I was actually thinking more family-like? /tween level. Like bullies going back to help the kids of the people they bullied? by going back to high school. The idea was to empathetic by being forcing them to be like the victim. I left it generic because I was thinking different people and different 'cases' for a TV series, not a movie.? But was definitely thinking younger audience, light dramedy with meaning.? So can look at different specific exampales and that should help create the tone.

"Stuck in limbo, the spirit of a cold blooded hitman must save the daughter of his latest victim from the mafia boss who hired him, in order to rest in peace."

Or:

"Stuck in limbo, the spirit of a cold-blooded hitman must save a girl from the mafia boss who hired him to kill her father, in order to rest in peace."

I wanted to make "people they hurt" more specific and what can hurt more than murder? (Maybe lots of things, but murder will do just fine.)