After drinks at a favourite Chicago hangout, Danny Martin (Rob Lowe) and Debbie Sullivan (Demi Moore) head to Danny's place to indulge in the predictable singles quest - the one-night stand. Their affair is casual, sensual, and supposedly over until something surprising happens. They want to see each other again. It's the start of an intense relationship that irritates Danny's rowdy best friend (James Belushi) and astounds Debbie's cynical buddy/roomie (Elizabeth Perkins), who do everything possible to break them up. But, Danny and Debbie wind up living together, and midst the daily drudge of domestic life, they begin to realise that making love is easy, saying I love you more difficult, and being in love the hardest of all.