What is the main plot and conflict builded up on the devil's arthmetic?

Hannah initially demonstrates an apathy toward her own heritage. She has no interest in going to the Passover Seder dinner and sees it as something to be endured rather than to be celebrated. Hannah is bored celebrating the Jewish holiday with her family. When Hannah rises from the table to symbolically open the door for the prophet Elijah, she is transported to Poland in 1942. There she inhabits the life of Chaya Abramowicz. There she experiences first hand her heritage and the atrocities her people experienced during WW2.

This concept, that the present is a living product of the events of the past, echoes throughout the novel. Consider how casually Commandant Breuer decided who lived and who died in the camp. Without any real consideration, entire bloodlines and family trees were destroyed. As a result the families of survivors have a greater appreciation of their own lives, knowing that their ancestors were able to survive a horrific ordeal and should not be forgotten.

Wow...too much info.