Nobody knows but you

"Kayla is still holding on to Lainie's secrets. After all, Lainie is Kayla's best friend. And despite Lainie's painful obsession with her on-again, off-again boyfriend, and the ways he has tried to come between them, friends don't spill each other's secrets. They don't betray each other's trust. The murder at the end of the summer doesn't change all that"--From the publisher's web site.