[1] NASA Professor Andrew Boran is a research scientist who discovers strange radio signals in outer space that appear to originate from Earth.

When he and his wife Sylvia decide to investigate the source of the signals, they end up being held captive in a convent that has been infiltrated by aliens.

While posing as the human Father Pergado, the alien leader Zindar explains Earth is a hotbed of disease that cannot be permitted to continue polluting the galaxy.

To make the return safely, Zindar holds Sylvia hostage and demands that Boran steal a Variance Crystal from the lab so that they can escape the destruction of Earth.

[4] Lee claimed subsequently that the producers misled him about the cast in order to secure his participation: I was told quite categorically by the producer that they had Arthur Kennedy, Richard Basehart, José Ferrer, John Carradine--I was told categorically that these people were signed to do this film.