Your heroine did something terrible in her past, something she had to do, but hasn’t been able to forgive herself for.
Desperate for answers, a psychic gives her a clue on how she can move on.
What does the psychic say? (Maybe she doesn’t go see a psychic, but rather the psychic/medium stops her on the street and says she has a message).
What did your heroine do and why can’t she get past it and forgive herself?