Joe and Kate are environmentalists who think they'll be videotaping evidence of toxic dumping. However, what they come across looks like a drug deal. They see the "seller" cut his hand with a knife then place a big leaf on it. His wound instantly heals. He's selling a special seed, which obviously has miraculous healing abilities. But when the two are spotted, the snipers fire after them. The guy selling the seeds is shot, drops it, and it soon starts sprouting roots and burrowing into the earth. Within moments there's a mini-earthquake, with massive roots grasping out of the ground. They flee in their car and barely get away, it's growing so fast.
Then we go to government agent Jack Taylor (Adrian Pasdar of HEROES) who wants to stop this giant malevolent root system. He recruits botanist Jocelyn Snow. She recounts, which is shown in a flashback sequence, how she and a colleague, Marcos (James Morrison of SPACE: ABOVE & BEYOND), discovered ancient seeds that were believed to be from the Garden of Eden. And these are some of the seeds, which have adversely reacted to our planet's now toxic environment and is going on a rampage. They confront Marcos and he insists that this wasn't his intent, that as long as the plants have clean soil they'll help mankind.
I found the story interesting but there's just one too many bible references and dialogue like "It's been proven that stories in the bible actually happened". For the most part the computer-generated effects are well-done, though I found it silly that the roots act like octopus tentacles and repeatedly grab people, for no reason other than to grap them. Does it like "squeezing the Charmin? THE TERROR BENEATH is sort of a more visceral take on M. Night Shyamalan's THE HAPPENING crossed with a 50's monster flick. Weird.