Junior (a early deceased Kevin James) is obsessed with and in love with his sister, the sexy Sherry (Dorothy Le May, frankly "at her best"). They run into Barbara (Kay Parker, still dazzling) on ​​the street, and Junior asks for her address under the pretext of returning some tools that her son Paul once lent him. Later that same afternoon, while Barbara is receiving an erotic massage in her living room from her friend Gina (the incomparable Juliet Anderson), the doorbell rings, and it turns out to be Junior, who arrives carrying an industrial toolbox ("Tools instead of flowers, how original," Gina remarks sarcastically in a now-memorable line). The resulting threesome is intensely erotic, and Junior ends up discovering everything related to Barbara's past sexual encounters with her son Paul, which practically compels him to do the same with his mother (the great Honey Wilder at her peak).

The "Taboo" series, directed by Kirdy Stevens, was a controversial success upon its release, so it seemed quite obvious that there would be sequels (perhaps too many). The first installment broke the mold with its depiction of incest between mother and son, and with this sequel, they aimed to go even further by breaking other taboos as well (brother-sister, father-daughter, etc.). Incest, a topic generally considered unacceptable in Western culture, was a very popular theme in adult films during the genre's golden age (although it now seems to have resurfaced with more fervor than ever in 21st-century porn). After tackling it in the successful original film, Kirdy Stevens and screenwriter Helene Terrie abandoned any inhibitions about its treatment, making "Taboo II" the next in a series of installments.