The Hardy Boys / Nancy Drew Mysteries (1977)

S1E2 The Mystery of Pirate's Cove

Nancy and her friends notice a mysterious beam of light emanating from an old, abandoned lighthouse. When they alert the local sheriff, he dismisses their claims, believing they are merely imagining things since the light has vanished. Determined to uncover the secrets surrounding the eerie lighthouse, Nancy takes matters into her own hands. As she delves deeper, she becomes entangled in a perilous web of crime that puts her life at risk.