Baywatch S09 E05 The Natural

"Cause I'm always ready, I won't let you out of my sight"

A mysterious figure called "The Phantom Lifeguard," begins making rescues and disappears before being identified by anyone. While Mitch thinks the Phantom Lifeguard is an outsider, Cody and J.D. think the unseen hero of the day is getting his/her information from inside the department.