It is 1975. A young JT is called out to the backyard by his mother to watch a meteor shower. The meteor shower starts off as fun but quickly turns scary as the meteors begin falling to earth on JT and his family's property. They rush inside and hunker together for the night as the meteors rain down together. Soon, people realize that the "meteors" are actually capsules containing seeds or spores for invasive plant species. At first, it seems there's just one species -- fern men which are growing taller by the day -- but people soon realize there are hundreds, if not thousands of different species of invasive plant. In the meantime, life goes on -- JT's parents split up, and this his mother remarries another man, Arnaud, who JT hates. JT dreams of becoming a scientist himself and studying the invasive plants to find out why they're here. The entire time, he has been sneaking a fern man around, who keeps getting taller and taller.

In time, JT goes to college and is writing an honors thesis in biology. At a bar, he meets Doran, a man he will eventually marry, and discusses his working theories about the invasive plants -- they all work without pollination, meaning they are manufactured, not naturally occurring.

Years later, JT has married Doran, and they adopt an Indonesian orphan together, Christina. JT's father has disowned him for being gay, and his mother has re-married, again. JT is studying the plants as a researcher.

JT goes to investigate his father, who has stopped showing up for work. The house has been taken over by the fern man. His father is dying inside of the house, where he congregates with leaves and vines.

Now, JT is older, and he has grandchildren, all of them scientists. Christina has figured out a way to make the plants edible, meaning things are finally looking up for humanity.

Finally, JT is an old man, surrounded by family members he thinks are strangers. His granddaughter gives him a flower.