For the first time in the 30-year history of the Star Trek TV shows, the population of Earth will be in grave danger.

Enterprise executive producer Rick Berman promises that the May 21 season finale -- called "The Expanse" -- will radically change the latest "Star Trek" series and set the show on a new course.

"For the first time on a 'Star Trek' series, we're going to be dealing with a mission to save Earth," Berman said in an interview with U.K. magazine Star Trek Monthly.

The season finale will end as a cliff-hanger setting up set the spaceship's Earth-saving mission to last much of show's third season, he said.

"There will be changes in a number of our characters . . . We're going to see changes as we go into a very ominous section of space, and try to find an alien race that we have reason to believe is going to do everything it can to destroy Earth's population," he said.

"So we're going to set up a lot in the final episode," Berman said.

"We'll be meeting some recurring characters we haven't met before. And we're going to be involved in a rather ominous task. That's the direction we're interested in taking the series in Season Three, and the finale will set that up in a very dramatic way," he said.

Enterprise is the latest incarnation of the Star Trek empire -- a franchise that has spanned more than three decades and included 10 movies and five different television series.

The two-year-old show revolved around the adventures of the crew of one of the first starships invented by humans.

It is a prequel that takes place about 100 years before original show's character, Captain Kirk goes into space.