“THE DOOMSDAY EXPRESS!” Batman and the Metal Men have all agreed to take part in a train ride to celebrate America's Bicentennial. Unexpectedly, the Metal Men receive a letter that suggests their creator Doc Magnus may still be alive!
To celebrate America's Bicentennial, an antique train, Old 76, is pressed back into service. On it's journey across the country, Old 76 will be carrying the Constitution and the Declaration of Independence, along with several other historical attractions, for the viewing pleasure of the American people. As special features, Batman and the Metal Men will be onboard, directing exhibits on Criminology and Robotics, respectively. Just prior to departure, the Metal Men receive word regarding the condition and whereabouts of their creator, Doctor Will Magnus, The Metal Men opt to investigate, promising to board the train at another junction. Batman boards Old 76, along with the curator of the train's historical exhibits, Professor Charles Wing, his assistant, Dolores Lake, and the chief of security, Ed Fox. Old 76, dubbed "The Liberty Express", makes stops all across America, and is wildly successful. Passing through the heartland of America, Batman becomes aware of boarders on the train's roof. Batman quickly ascends to the train car's roof, only to find Fox waiting for him. The security chief pistol whips the Caped Crusader, rendering him unconscious. Batman awakes to find Wing, Lake and Fox standing over him, in full Native American regalia. Their true names are Charlie White Wing, Dolores Clear Lake, and Eddie Running Fox. Along with their Indian brothers, the trio have commandeered the Liberty Express. Unless the President of the United States makes serious reparations to the Native American tribes, White Wing will destroy both the Constitution and the Declaration of Independence. Realizing that they've been sent on a wild goose chase, the Metal Men make plans to re-board the Liberty Express. With the train stopped for refueling, the Metal Men steal onboard, each in their own inimitable fashion. With only 12 hours remaining before the President must answer White Wing's ultimatum, the Metal Men have no time to lose.
Their first order of business is to free the Batman. Next, Iron and Lead uncouple the car holding the Constitution, and the Declaration of Independence, from the rest of the train. The slow moving Lead, however, is spied by one of the Indian terrorists, who raises the alarm. Before he has a chance to mount a counter-offensive, Batman is ambushed, and subdued by the Indian boarding party. Further up on the tracks, Gold, Platinum, Mercury, and Tin set up on a spur track diverging from the main line. With Gold, Mercury, and Platinum fashioning themselves into a switch, Tin prepares to divert the train down the spur track, into a dead end, while Iron and Lead escort the uncoupled car down the main line. As the train rounds the bend, however, the Metal Men are horrified to see the Batman lashed to the train's cowcatcher. Tin cannot divert the train, for fear of Batman being killed when it reaches the dead end. The uncoupled car forcefully impacts the train, dislodging Iron and Lead. With the train once more whole, the Metal Men rush to re-board before it travels too far from their position. The indians unlash Batman from the cowcatcher and bring the Caped Crusader back onboard. As the Liberty Express nears White Wing's ancestral home, the Indian leader spies smoke signals on the horizon, relaying a message from Washington, D. C. Foreign terrorists have planted a bomb, somewhere onboard the Liberty Express, set to go off in one hour. United by a common cause, Batman , the Metal Men, and the Indian raiding party mount a desperate search for the bomb. All seems lost until White Wing notices historical discrepancies in the painting of Custer's Last Stand. The back of the painting is revealed to be coated in plastic explosive. The bomb is launched from the Liberty Express by the Metal Men, but the explosion starts an avalanche that Old 76 is barely able to escape. Impressed with the nobility and courage of the Batman and Metal Men, White Wing has a change of heart and relinquishes his hold on the Liberty Express. In return, Batman offers to help White Wing win back his people's rights from the United States Government.