Doctor Doom has captured the Fanastic Four, taking them to his treacherous castle.

Sue learns about Doctor Doom's past, while the others deal with the castle's traps. When they find him, Doom offers a deal: travel back in time to retrieve an ancient casket or Sue will be killed.

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.