The Devil's Arithmetic
Hannah (Kirsten Dunst) is a spoiled Jewish American teen who has no appreciation for her heritage; several older members of her family are Holocaust survivors. Hannah carelessly gets drunk and passes out at a family celebration.
She "awakes" as "Chaya" in a WWII Polish ghetto, is hauled to a concentration camp, and befriends a girl named Rivkah. After coming to realize where she is (and when), and spending months in the camp, Hannah finally gains a little perspective on her family. After much hard labor in the camp, Rivkah is ill and going to be taken to the gas chamber. Hannah/ Chaya realizes that Rivkah is in fact the younger version of her Aunt Eva; Hannah/Chaya convinces the guards that she is the sick one, and Rivkah is spared. "Chaya" perishes.
When modern-day Hannah awakes, she lovingly greets Rivkah, whom Hannah has known all her life only as Aunt Eva. Eva is stunned that her old name is used, and Hannah explains that she understands so much more now.
We see Hannah joyfully taking part in the now meaningful ceremonial celebrations that she had mocked before.