"Assault on Engine City!"
Continued from Superman (1987) #81, continues in Action Comics (1938) #691.
Superman, Steel, and Superboy launch their attack on Engine City as the Cyborg Superman ponders the identity of the individual travelling with Steel and Superboy. When it is revealed that their companion is the real Superman, Mongul mocks the cyborg who quickly puts the villain back in his place.
Working their way through the immense machine city to thwart the evil cyborg's plans for attacking Metropolis, the trio encounter wave after wave of Warworlders until they find the intended instrument of Metropolis's destruction.
Upon launch of the horrible weapon, Superman and Steel barely escape being burned to death but Superboy latches onto the massive rocket in an attempt to stop it. As the missile draws nearer to Metropolis Superboy succeeds in steering it off course but it detonates over the Atlantic ocean with him still clinging to it - all televised worldwide. How could anybody survive a blast that would have been big enough to destroy the largest city on Earth?