Within minutes of arriving on screen, Kate (Mary Elizabeth Winstead) drunkenly wets her bed, sloppily teaches her kindergarten class, and wraps up a night of partying by smoking crack at the local homeless hangout. Mixing gallows humor with pitch-black observations about addiction, James Ponsoldt's feature starts off as an exhilarating dark comedy. But it quickly gets serious, and the sense of humor dissipates. Aaron Paul stars as Kate's husband, equally as dependent on drink as he is on her shared taste for self-destruction. When she hits rock bottom — faking a pregnancy to justify throwing up in class — a fellow teacher (Nick Offerman) forces her to clean up, but getting sober with a drunken beau proves impossible. The stage seems to be set for a boozed-up Blue Valentine, but just as the melodrama gains traction we cut to a coda and the credits (it runs a scant 85 minutes, and feels unfinished). The film is at its best only when its characters are at their worst.