Maryjane tells the story of high school art teacher Phil Blake (Fabian) during the counter-culture and the beginning of the war on drugs. Blake tries to convince those in authority, including the principal, that marijuana isn't a bad thing. He soon finds several of his students have been introduced to smoking "maryjane." Blake tries to talk with the students about drug use, even admitting to trying pot a few times during college, but he soon finds a ring is operating at the school to distribute the drug. Blake has also fallen for fellow teacher Elli Holden (Diane McBain), who is struggling with her own emotional issues. Those romantic feelings are tested, however, when Blake discovers Holden is the lead drug dealer at the school with help from the high school football team star. Blake is framed for possession of marijuana and arrested while trying to help the students stay out of trouble.