An accident at a nuclear research facility creates a dimensional doorway in which aliens need to widen to invade our world. A scientist races to discover a way to reverse the damage and close the doorway.
Did You Know?
This episode features a number of actors who would later appear in Star Trek, including Rudy Solari, Joseph Ruskin, Leonard Nimoy, Barry Russo, Willard Sage and Vic Perrin. See more
After Dr. Marshall finishes assembling the fusion bomb, he leaves it in the fissionable materials vault and locks the door. He is still inside at the time, and there is no other way for him to leave the vault. See more