""This X, this unknown quantity, has forced its way through miles and miles of solid rock. How's a couple feet of concrete going to stop it?"
- James Bernard's shrill, panicked score.
- The titular "X": an amorphous mass of living, radioactive mud from miles underground. Getting too close will, at best, give you fatal radiation burns. It's about as vulnerable to conventional weapons as you'd expect. The more radiation it absorbs, the bigger it gets, and the greater the risk of a nuclear explosion...
- In the hospital radium room, Dr Kelly and nurse Zena meet up for some fooling around. Somehow, the machine is switched on. Something then corners the terrified Dr Kelly, causing his hand to severely swell. To Zena's horrified scream, Dr Kelly's face boils right off his skull.
- On a winch, Peter is lowered into the fissure's unknown depths - where, on a ledge, lies a soldier's skeletal remains. Peter's Geiger counter then starts crackling. He looks down...Peter: Get me out of here... GET ME OUT OF HERE, QUICK!!
- Major Cartwright has the fissure bombed and concreted over. Soon enough, the concrete splits, and X oozes forth...
- X, now hundreds of feet across, slides towards the Research Establishment. On its way back to the fissure, it swamps an entire field.
