Synopsis by Mark Deming
An invisibility formula becomes the target of a network of international criminals in this sexploitation opus from the 1960s. Poontag Plenty (Joyana) is a sultry female secret agent working with the international espionage organization S.I.N., which operates out of an apartment in a run-down New York City neighborhood. The sinister Dr. Sexus has hired top-level gangster Mr. Silk Suit for an important mission -- Silk Suit and one of Sexus' brawny henchmen are after Prof. L.D. Drake (C. Davis Smith), who along with his buxom assistant, Karen, has developed a drug that can make people invisible. Between Poontang's brazen charms and Silk Suit's talent for violence, stealing the drug ought to be a cinch, but Karen's resourcefulness and the presence of her boyfriend, Sam, a pinup photographer, make matters more complicated than they imagined. The Girl From S.I.N. was written and directed by C. Davis Smith, who served as cinematographer for most of Doris Wishman's classic sexploitation efforts; he also plays the hapless Prof. Drake.