Above the Earth, a meteor shower damages an alien spacecraft, which then falls down to the planet's surface. A giant humanoid alien emerges and makes its way towards New York. In the Fantastic Four's headquarters in the Baxter Building, Ben is helping Reed to install some heavy equipment when they are alerted to the alien's presence in the city by Herbie and Sue. Reed, Sue and Ben board the Fantasticar and find the alien threatening a city bridge, at the same time as the army, air force and navy mobilise themselves for an assault on the alien. Meanwhile, the alien has badly damaged the bridge, leaving it up to Ben and Reed to fix it while Sue follows the alien. It attacks the Fantasticar and captures Sue, forcing the planned air strike against the creature to be called off. Sue turns invisible and manages to escape from the alien, and Herbie informs the rest of the team that according to his analysis of the alien's thought patterns, any harm to the alien would place the whole planet in jeopardy. Sue turns the alien invisible so that the army has nothing to fire at and the Four return it to the crashed spaceship. The Four then have to protect the alien from the army and find out its secret.