The Blue Lagoon is based on a book by the same name and was directed by Randal Kieser. The film stars a young Brooke Shields and a relatively unknown male actor Christopher Atkins. Though the movie depicts a Victorian setting and Shields was only 14 years old when the film was made it garnered an R rating by the Motion Picture Association.
The plot of The Blue Lagoon is set in motion by a shipwreck in the South Pacific, which is survived only by two young travelers, cousins Emmeline and Richard, and the ship's galley cook Paddy. The trio manages to make it to shore only to find themselves on a deserted tropical island.
Paddy is accustomed to the rowdy life of a sailor but he takes on the role of surrogate father and goes about setting up suitable living arrangements for the children. He teaches them the basic survival skills they'll need to practice until they are discovered and rescued. Unfortunately it isn't long before Paddy succumbs to a drinking binge and Richard and Emmeline are left to fend for themselves.
The children manage to thrive and even flourish in their own little world. They develop into handsome and healthy but extremely naïve teenagers. The story focuses on the tension the teen's growing confusion places on their relationship and situation. By necessity both had gotten used to going naked but now suddenly were embarrassed about the changes in their bodies. In a particularly revealing scene Emmeline is terrified when she starts her menstrual period and Richard is convinced she must have cut herself to be bleeding so heavily.
Emmeline's feelings are laid bare when she lets an opportunity for rescue slip by and fails to signal a passing ship. Richard is at first furious but ultimately understands her motives and forgives her. Their bond and commitment is cemented even further. It seems a natural progression when the cousins begin having sexual intercourse although their naivety is emphasized when Emmeline becomes pregnant and neither has a clue that a baby is on the way.
Nature takes its course and Richard helps Emmeline deliver a healthy baby boy who they name Paddy. Basic instinct compels Emmeline to hold the infant to her chest and the baby to suckle. The young family endures some harrowing plot twists before being rescued by none other than Richard's father who it turns out had never stopped searching for his son.