The Gift of Life - S1.E14

A bride to be complains that her father is not present at her wedding, but as she speaks she falls down a flight of stairs and dies.

When she meets Othniel he claims that she can still save her dead sister, if she can only put aside her hatred for her estranged father.

She returns (as a doctor) to a time just before her sister's death, and is told that she must find their father to get a bone marrow sample, so that her sister can live on.

But neither the sister nor she knows where her father is. It's only when she confronts her sick sister that she finds out that she has a photograph of him, and a phone bill that has his number.

Reluctantly she tracks down the father, and develops some kind of understanding for him, but the father reveals a secret about her, that changes everything.