Late one evening, Steve Rogers sits in his Brooklyn apartment, working on an art assignment. Suddenly, a superhero costume with a British flag motif appears on his body for a few seconds, then vanishes as mysteriously as it came. Struck by curiosity, Steve decides to investigate the only clue he has, and he packs a bag and heads for England….
Out on the streets, Nomad (Jack Monroe) encounters a gang of Punk types robbing a deli. They mock this newcomer, then charge. Distracted at first by their taunts, Nomad soon focuses and takes down the crooks, While the hero checking that the store owner is okay, the punks escape. The owner gathers all the stolen money and responds to his rescuer with "Thanks again, Captain America!"
Arriving at Heathrow Airport in London, Steve dons his Captain America costume and heads downtown via a combination of train (riding the roof, swinging on flagpoles and running across rooftops. As he crouches admiring the beauty of the city at sunset, he is suddenly blasted from behind and turns to face…Captain Britain. Cap dodges the attacks of the more powerful—and strangely hostile—English hero and seizes hold of his opponent’s ankle. Brit then flies at high speed, crashing through the dome of St. Paul’s Cathedral, and then stops short, letting inertia carry the American far over the skyline….
[In America, Steve’s girlfriend Bernie Rosenthal stops by his apartment looking for him and discovers the puzzling note that he has gone to England….]
In London, Cap finds himself heading straight for the Post Office Tower and manages to grab onto the supports and halt his flight. Cap Britain follows him and Cap A again leaps on his foe and they trade punches in mid-air until the more powerful hometown hero sends Cap to the ground and drops a building on him….
Cap awakens in a dungeon with another prisoner who turns out to be the real Captain Britain. The bogus hero unmasks to reveal Modred the Mystic, the sorcerer he once encountered with the Avengers. Left amnesiac and powerless in Europe, Modred soon wandered back to England, his memory and magic returning to him on the journey. Once in his native land, he recalled his mission to destroy the mighty Merlin, and encountering Captain Britain, decided to help himself to the hero’s body armor. Brit sent his costume mystically to Steve for safe-keeping but he sinister wizard was able to retrieve it almost instantly. And now, having dealt with Captain America as well, only one step remains for Modred: summoning Merlin…to his death….