Sibling astronomers discover Martians are threatening to attack Earth, but no one believes them, until Martians land and nearly destroy all of New York City. As the siblings try to make it out of the city with their families, they discover the Martians have no immunity against the diseases of Earth, and must now figure out how to infect the invading army to eradicate the aliens before all of Earth is destroyed first.

Sibling astronomers join forces with the military when hostile aliens attack Earth.