Baywatch - Season 8 Episode 19
Diabolique

Mitch rescues a troubled young woman, named Sara, from her boat after it catches afire after which she charms Mitch and gets his mother, Irene, to hire her as a nanny for Neelys baby, Ashley. But Mitch gets concerned when Sara quickly develops a dangerous obsession with him and tries to win his affections at any cost. When Mitch lets Sara down, she immediately shows her true colours and plots to make Mitchs life a nightmare.