With the occasion all but overshadowed by her sister’s upcoming wedding, angst-ridden Samantha (Molly Ringwald) faces her 16th birthday with typical adolescent dread. Samantha pines for studly older boy Jake (Michael Schoeffling), but worries that her chastity will be a turnoff for the popular senior. Meanwhile, Samantha must constantly rebuff the affections of nerdy Ted (Anthony Michael Hall), the only boy in the school, unfortunately, who seems to take an interest in her.
Lane Meyer (John Cusack) is a teen with a peculiar family and a bizarre fixation with his girlfriend, Beth (Amanda Wyss). When Beth dumps Lane, he decides to kill himself, making bumbling attempts at suicide. Outside of his morbid endeavors, Lane spends time with his oddball buddy, Charles (Curtis Armstrong), and befriends Monique (Diane Franklin), a visiting French student. Eventually, Lane resolves to race Beth’s obnoxious new beau on the ski slopes, with unexpected results.
Young Ben Crandall (Ethan Hawke) spends his free time watching sci-fi films, playing video games and reading comic books. Surprisingly, his affinity for all things fantastical yields a real result — when he has a vivid dream about technology, his science-loving friend Wolfgang Muller (River Phoenix) manages to create a working spacecraft. Joined by their buddy Darren Woods (Jason Presson), the boys take off into outer space and encounter some very odd extraterrestrial life.