X The Unknown (1956)
While going through some routine practice training in Scotland for mine
detection a group of soldiers detects a large radioactive signal just
before the ground opens up in an explosive eruption. They summon
plutonium scientist Dr. Adam Royston (Dean Jagger) for advice as to what
to do. When Royston has his own lab destroyed he surmises that the culprit
was un-human, and when two soldiers guarding the large crevasse where the
ground erupted disappear he understands that there is some chemical force
at work. The Army decides to block up the ground with concrete but Royston
knows that the force will come out for more radioactive material and prepares
for it. When it is revealed by Dr. Royston that the monster is actually a mass
of energy he gets ample resistance form the voice of reason, the Army generals
at hand who decide to bomb the thing back to the center of the earth where it
came from. In a final showdown with the force taking a horrible new form
Royston and the Army fight for their lives. (IMDB spelvini)