He wants his ‘machine men’, his robots, to be used particularly in the mines, where miners often carry out highly dangerous and physically demanding work.

Heller mistakenly considers his most capable scientist, Professor Wolf, the most important supporter of his vision of a ‘better working world’.

On a business trip, Heller inspires fellow traveller Werner Baumann, a mining engineer, with his vision of man and machine merging into a single entity to the benefit of mankind.

Baumann has barely returned to his colliery when a devastating firedamp explosion kills numerous miners.

When Heller, who is appalled by Wolf's unauthorized and bizarre research activities, gets too close to the killer robot, he is hit by its deadly rays.