The Skrulls, a race of green skinned shape shifters, come to Earth and impersonate the Fantastic Four. They attempt to discredit them, hoping to keep them from interfering in their plans to conquer Earth.

The enigmatic Watcher warns the Fantastic Four of the impending arrival of the herald of Galactus, the Silver Surfer. They learn if he summons his master, all of Earth will be devoured.

As Galactus' plans unfold, the Fantastic Four try to reason with him, but it proves futile. The only way to defeat Galactus now, puts Johnny's life in mortal danger. Meanwhile, the Silver Surfer sees Alicia and his loyalties begin to change.

The Skrulls let loose a new danger for the Fantastic Four to face, a being that possesses their combined powers: Super Skrull! Will the team be able to take this villain down?

Reed, Johnny, and Ben arrive in ancient Greece, with only forty-eight hours to find the casket. Their problems multiply, however, when they get into the middle of the Battle of Thermopalye.