The Sign in the Smoke, Paperback

Nancy and her friends are faced with another chilling mystery in this twelfth book of the Nancy Drew Diaries, a fresh approach to the classic mystery series.
When Bess asks Nancy and George to be counselors at her old camp, they're a little wary. After all, running around after a bunch of little kids doesn't exactly sound like funBut Bess promises that the girls will get to enjoy nature, relax by the lake, and play some sports. Plus, it will give Nancy a much-needed break from solving mysteries.
But trouble always finds Nancy DrewAfter hearing the disturbing tale about a camper who had drowned in the lake years ago, Nancy dismisses it as a ghost story. But then something pulls her under water during a swim lesson--something eerily human, with long, silvery hair. And the next night her entire cabin's sleeping bags disappear--only to show up at the lake, soaked.
Now Nancy isn't so sure if she believes in ghostsAll she knows is she has to do everything within her power to make sure her campers--and her friends--are safe. Which means she'd better get to the bottom of what's happening at Camp Cedarbark.