Lena and Ethan tell Aunt Del and Reece that they're studying genealogy so they need to do a grave rubbing.
They find Genevieve's headstone. Oh, and Genevieve. Her ghost is standing near her grave. Grave digging sure goes a lot faster when your family members have special powers.
They all join hands so Aunt Del can take them on a trip through time. She's almost like a human version of Genevieve's locket.
Just like that, they can see everything that's happened in the physical place where they're standing:
(1) A young Genevieve chasing a young Ethan Carter
(2) Genevieve trying to bring him back to life
(3) Genevieve's funeral, complete with Ivy tossing The Book of Moons into the casket
He knew it!
When Ethan finally digs up the book, touching it singes the skin off his fingertips. Ouch.
After the whole thing's over, Lena uses a Caster trick to erase the whole event from Aunt Del's and Reece's minds.
She explains to Ethan, "I Shifted the Book out of their minds. […] In their reality, it never happened" (12.07.131).
Ethan feels weird about it, "like a line had been crossed" (12.07.132)—and he doesn't mean the Mason-Dixon line.
Then, when Ethan tries to return the locket to Genevieve, her ghost tells him that the locket doesn't belong to her.