Hawaii Five-O (1968)

S1E16 Up Tight

Eadie Hastings, a young girl, tragically leaps off a cliff before Danno can intervene, leading Five-O to suspect she was under the influence of speed. Their investigation leads them to a drug-dealing teacher, Professor David Stone. To uncover the truth about the drug's distribution and its users, Danno goes undercover as a surfer, navigating the dangerous world of drug pushers to gather vital information.