Adventures of the Super Sons #10
Its the runaway train from hell! Superboy and Robin better hold on for dear life as they ride a 20-megaton cosmic engine of mass combustion (thats a pun!) into their final battle with Rex Luthor! But Rex has got a brand-new army of shiny young super-villains ready to conquer all they survey...will the son of Batman and the son of Superman be enough to stop him?