Set over the course of one long stag night before the wedding of Hal (James Purefoy) and Vinni (Susan Vidler), Stag Night is a comedy of errors that presents its audience with a dizzying array of half-baked schemes, compromising positions, and lust-driven machinations. Hal is a womanizing photographer who has cold feet about his impending wedding. With the help of his friend, cartoonist Little Ted (Tony Slattery), he cooks up a plan in which another one of his pals, swimming coach Mr. Mac (Adrian Dunbar), seduces Vinni and thus relieves Hal of his marital obligations. However, Little Ted still nurtures a longing for Vinni, who dumped him awhile back, and thus convinces Mr. Mac's girlfriend, barmaid Petula (Amanda Redman), to seduce Hal into posing for some dodgy Polaroids. To top it all off, Petula's husband is getting increasingly suspicious of his wife's pastimes, Vinni's best friend Cloudah (Victoria Smurfitt) slept with Hal only a couple of days ago, and Vinni, it turns out, has her own reservations about the wedding.