The film follows the events after NASA launches a space probe to collect samples and verify the existence of extraterrestrial life in our solar system. Upon reentering Earth’s atmosphere, the space probe crashes in Mexico, releasing alien life forms that quickly spread and cover half the country.

The northern half of Mexico is quarantined, and soldiers from both the United States and Mexico attempt to eradicate the aliens with all their weapons, but ultimately fail. The United States decides to build a massive wall along the US-Mexico border to protect its citizens, leaving Mexico to fend for itself against the creatures from outer space.

American photojournalist Andrew Kaulder (Scoot McNairy) is in San José, Central America, working on a story he believes is his big break. However, his supervisor assigns him a new task: to find Samantha Wynden, the daughter of the publication’s owner, who was injured in a hotel incident last night.

Andrew locates Samantha (Whitney Able) in a Mexican hospital, and they board a train bound for the coast. However, their journey is interrupted when the conductor announces that the train must turn around due to damaged tracks ahead. Andrew decides to disembark at the next station and find another way.

They realize that they are in the middle of nowhere. Luckily, they find a kind woman who let them stay at her house for a night. They learn that they are still over 100 kilometers away from the coast, and nobody travels at night because of the creatures. And the military will close the whole coastline in two days, if they are unable to reach the coast within the next 48 hours, they will be stuck here for the next six months.

Monsters is not the science fiction film it appears to be; rather, it is a road trip film with aliens that largely remain in the background. The audience watches as two characters interact while struggling through a hauntingly beautiful post-apocalyptic landscape, accompanied by the equally wonderful music of English musician Jon Hopkins.

I find the story to be quite a slow burn without a clear climax. The film simply meanders on without a clear objective, culminating in an unremarkable ending. Moreover, I find it puzzling that the filmmakers chose to depict the aliens as giant squid with tentacles. How, by any comprehensible logic, could an extraterrestrial mushroom transform into a squid?

MONSTERS premiered at the South by Southwest Film Festival on 13 March 2010, and was theatrically released in the United States on 29 October. The film, which was produced on a budget of $500,000, has grossed over $5 million worldwide.