As the fireworks explode outside, Amber and Sarah, stepsisters bound by blood but not by choice, find themselves in a shared bedroom, the tension between them palpable. Their stepbrother Anthony, home for July 4th, enters, catching them in a compromising position, their hands wandering under the covers. In the spirit of the holiday, they decide to celebrate their freedom in the most taboo way possible, their bodies entwined in a threesome that's as explosive as the fireworks outside.