Joon-ho Bong’s “The Host” successfully mixes a monster with family drama, comedy and political satire.

In a South Korean laboratory, an American scientist orders dirty formaldehyde bottles to be dumped into the Han River, ignoring his assistant’s objections. In a salute to the monster genre, the formaldehyde creates a giant mutant tadpole. Gone are the days when radiation produced such beasts.

A deadbeat father, Park Gang-Du (Kang-ho Song), his preteen daughter, Park Hyun-seo (Ah-sung Ko), and her grandfather, Park Hie-bong (Hie-bong Byeon), run a snack stand at a Seoul riverside park when the amphibious beast appears, causing havoc.

Gang-Du charges the creature with a road sign but only succeeds in squirting himself with monster blood. As he retreats, Gang-Du mistakenly grabs a girl that is not his daughter. When he realizes his mistake, it’s too late. Hyun-seo has been taken by the creature.

Gang-du and Hie-bong sob over a picture of their little girl at a gym of mourners. Gang-du’s sister, Park Nam-Joo (Du-na Bae), arrives followed by her drunken brother, Park Nam-il (Hae-il Park). Pulling and tearing at each other in anger and sadness, they collapse in a heap, attracting the authorities. The family is hospitalized when officials learn that Gang-du was sprayed with the creature’s blood.

Where the monster in the original “Godzilla” was an allegory for Japan’s nuclear Holocaust, “The Host” is a metaphor for U.S. occupation. Deeming the South Korean response to the creature as lackluster, the U.S. military installs itself in the country. American scientists announce that the creature is host to a deadly virus, though Gang-Du overhears that there isn’t a virus at all. It’s a fear tactic to keep the population in check.

Later, the script becomes fragmented as if each subplot must exist independently of the other before changing gears.

The film remains enjoyable within the various genre moments, as the filmmakers offer their own quirks on the conventions. “The Host” is a thoughtful romp in a genre not known for its intelligence. It delivers a commentary on family dynamics and military occupation, but it doesn’t take itself too seriously. Viewers will find humor in the most unexpected places.

“The Host” was written by Chul-hyun Baek, Joon-ho Bong and Won-jun Ha, and directed by Bong.

“The Host” received 3.5 out of 4 stars.