When Debbie Holten and her friends find her little sister's body sprawled on the beach at the bottom of a thirty-foot drop, they're terrified. Mallory's fall was her own fault, but the four kids are sure they'll get blamed.

Debbie's still trying to find her place in her new foster family. The last thing she wants is to give them a reason to send her back. In a panic, they hide Mallory's broken body in a cave, hoping her "disappearance" will be easier to explain to the adults. And it works.

For a while.

On the first anniversary of Mallory's death, one of the group turns up dead. The kids try to explain it away—but each "death-versary" brings about more horror and tragedy.

Debbie knows her baby sister's death was an accident...but it seems Mallory's spirit disagrees.