Gross-out horror is never far from comedy, and The Host, Bong Joon-ho's giddy creature feature, is a broadly played clown show full of lowbrow antics -- itself a sort of monster as the top-grossing movie in South Korean history. The main attraction is a killer tadpole: It's an "It." Bong's allegory is deliberately free-floating; still, that the thing has its origins in American hubris is made clear in the prologue, set in a morgue on a U.S. Army base, where an overbearing American officer orders a hapless Mr. Kim to dump gallons of toxic chemicals down the drain and into the Han River. Cut to picnickers on the riverbank, transfixed by something suspended beneath the bridge. The "It" falls into the water and swims over. Ordinary people, being what they are, merrily pelt the unknown creature with garbage until, with projectile force, it bounds ashore, grabbing the 11-year-old Park family granddaughter in its fishy clutches. From then on, it's personal. For the Parks, the monster comes to embody whatever irrational forces oppress them. Meanwhile, authorities explain (rather illogically) that the creature was carrying a mysterious virus. But is it the It or South Korea who is really the host? As amorphous as its creature, The Host has an engaging refusal to take itself seriously -- and yet, however funny, it is hardly camp. The emotions that The Host churns up, regarding idiot authority and poisonous catastrophe, are raw. Is revulsion a form of revolt?