American satellite X-117, carrying a
chimpanzee, has unexpectedly fallen back to Earth after entering a non-existent/fictional part of the
stratosphere known as "the flame barrier", which encircles Earth at an altitude of 200 miles. Howard Dahlman (Dan Gachman), a rich businessman and ardent amateur space program enthusiast, went into the Mexican jungle to recover the satellite, but never returned. His wife, Carol (Kathleen Crowley), sets out to find him. Arriving in
Campeche, Mexico, Carol meets two jungle guides, the ill-tempered Dave Hollister (Arthur Franz) and his drunken but good-hearted brother, Matt (Robert Brown). When she asks their help, Dave refuses, citing the coming rainy season. But he changes his mind after Carol gives in to his extravagant demand for $7,000 each for him and Matt if Howard is alive or 10 percent of his estate if he is dead. Dave asks Carol which is more important to her, Howard or the money from his estate. She hesitates before saying unconvincingly that she wants to find her husband alive. Carol, Dave, Matt and their native porters head into the jungle with a copy of Howard's map. It shows the route he took to the X-117 crash site, 200 miles from Campeche. In the jungle, they find a burned skeleton. Dave examines it and tells Carol that it is not Howard. Dave asks if she loves Howard. Carol says that she does not know and that perhaps this is what she is trying to learn on the expedition. In return, Dave says that he too had had an unhappy marriage. At their camp, Dave, Matt and the porters bring in a badly burned tribesman. Dave attempts to treat him, but the man dies. The porters say that the God of Fire is responsible. To everyone's shock, the man's body suddenly bursts into flames, leaving a skeleton similar to the one they had found earlier. Despite the rigors of the trek, Carol and Dave's mutual attraction grows. They kiss passionately later that night. One by one the porters run off, leaving Carol, Dave and Matt on their own. They soon find Howard's abandoned camp. It has
solar power and, surprisingly, the chimp from the satellite is there. Carol says that she is now convinced that Howard is dead, but Dave says that they must find Howard's body to legally prove it. A tribesman appears and takes them to the cave where he says the God of Fire lives. Inside the cave, they find X-117 surrounded by an alien blob, out of which Howard's perfectly preserved head protrudes. But the chimp disintegrates as it approaches the blob, which itself is surrounded by a deadly invisible electric field. Dave and Matt calculate that the blob doubles in size every two hours. At that rate, it will expand out of the cave and overtake them if they try to outrun it. Their only chance is to destroy it inside the cave. Dave notices that X-117 is sitting on two veins of metallic ore. He says that if they connect a
solar battery to both veins, they can perhaps electrocute the blob and kill it. But by the time they have prepared everything, they have only eight minutes before the blob again doubles in size. Matt climbs to the vein above the blob. Unfortunately, they have miscalculated and the blob suddenly begins to expand. Matt dives into the blob, sacrificing himself, but giving Dave just enough time to electrocute it. With the blob dead, Carol and Dave walk slowly away, arm in arm. == Cast ==