In book 7, everyone was expecting some miracle to happen after the elder died, but all that happened was that his body started to stink. Everyone thought this was a sign that the elder was secretly a sinner, but I think this goes back to the discussion Ivan and Aloysha had about men needing miracles to believe, but Jesus not wanting to force people to believe just because of miracles. Anyways, Aloysha had been upset, but then he went and saw Grushenka and she restored his faith.
In book 8, Dmitry was trying to find 3000 rubles, but nobody would give it to him. He thought Grushenka had gone to his fathers house, so he ran over there and was going to kill his father, but ended up hitting Gregory instead, and doesn't know if Gregory died or not. Then Dmitry went on a spending spree and saw Grushenka and her lover. Grushenka ended up choosing Dmitry. The police came and arrested Dmitry for the murder of his father. I had a lot of questions after reading this book. Where did Dmitry get the money from? Did he actually kill Fyodor? What is Dmitry's secret? Hopefully we find out soon.