The book fits specifically into the survival horror genre, which is marked by people doing whatever it takes to conquer their environment and stay alive.
They befriend a German tourist named Mathias, and a trio of Greeks who go by the Spanish nicknames Pablo, Juan, and Don Quixote.
Jeff volunteers the group to accompany Mathias as he attempts to find his brother Henrich, who went missing after having followed a girl he'd met to an archaeological dig.
The driver of the pickup truck who takes them to the outskirts of Coba tells Amy that the place to which they are going is "not good," and offers to drive the group somewhere else.
Near a Mayan village, they discover a disguised trail which leads to a large hill covered in vines and surrounded by bare earth.
They lower Eric after him, and he jumps to the bottom when they realize the rope isn't long enough, injuring his leg in the process.
As the group fashions makeshift rope from one of the tents, Eric discovers that Pablo's back is broken, paralyzing him from the waist down.
While the group remains optimistic that Juan and Don Quixote will arrive, following Pablo's note, Jeff makes preparations to ration food and water.
He also realizes that the vines only consume organic material, as the victims' passports, jewelry, and the Mayans' arrowheads and bullets are intact.
With their resources dwindling, Jeff decides to return to the mine shaft to find the cell phone, taking Amy with him.
Jeff realizes that there is no phone: the vines can imitate sounds they hear, and have been attempting to lure him and Amy into falling down another shaft to their deaths.
Jeff returns, infuriated that they drank alcohol with so little water between them, and that Eric has once again cut himself attempting to remove the vine from inside his body.
That night, while Jeff is on lookout for the Greeks, it begins to rain heavily, forcing the Mayans to take cover in the trees.
During the storm, Stacy takes advantage of the rain to bathe herself while Mathias watches over Pablo and Eric rests in the tent.
They return to camp to find him alive, but heavily injured, having cut off his own ear and flayed much of his skin in an effort to remove the vine.
A little girl, who is acting as a sentinel, as the little boy on the bike was, runs back to the village, but the new tourists are already halfway up the hill, calling for Pablo, before the Mayans arrive.
According to an interview with the Pittsburgh Tribune-Review, the book started as a trial run after a period when the novelist had concentrated on writing the screenplay for A Simple Plan.
Entertainment Weekly reviewer Gillian Flynn gave The Ruins an A−, calling it "Thomas Harris meets Poe in a decidedly timely story," continuing, "Smith has tapped into our anxieties about global warming, lethal weather, supergerms—our collective fear that nature is finally fighting back—and given us a decidedly organic nightmare.
"[3] Michiko Kakutani, writing for The New York Times, said, "As in his debut novel, A Simple Plan (Knopf, 1993), Mr. Smith is concerned with what happens to a group of ordinary people when they are suddenly placed in a decidedly extraordinary situation.
It seems meant to be a straight-ahead thriller, with some bloody set pieces lifted from the horror genre thrown in for extra chills: you know, grisly, up-close shots of people having their legs chewed up or being choked to death by demonic forces.
The Ruins is like all great genre fiction in its irresistible storytelling momentum, but in its lack of mercy, it's more like real life.
He paints each one like a great artist, yet also holds back, sharing only the bits and pieces of detail that you need to make the scene your own."
The reviewer added that it "has a strange duality in that it directly pays homage to Rod Serling's Twilight Zone, and indirectly to The Corrections by Jonathan Franzen.