Bill Plympton’s latest feature-length animation, about a loving couple riven by infidelity, contains some of his loveliest fantasy sequences, though the gap between his visual and storytelling skills persists. The grotesquerie of his characters has been widely noted, yet its importance to his work can’t be overestimated: his “Plymptoons” are fascinating primarily for the tension between his grossly exaggerated bodies and the evident care, even fussiness, of his scribbly, hand-drawn pencil shading. Plympton has a way of turning the perfect physique into something nightmarish—shirtless, his hero has an impossibly tiny waist but pectorals the size of a desk—and because of this, his lovers are so revolting that one can’t develop any sympathy for them. As in so many of Plympton’s other movies, the visual invention drives the story (by default).