FBI agent Topolsky returns to warn Liz that a covert alien hunter inside the Bureau is pursuing Max and his friends - and that he will stop at nothing to get what he wants. Meanwhile, Isabel befriends Tess, a new female student who immediately arouses Max and Michael's suspicions.
Max, Isabel and Michael have been hiding a secret for their entire lives - that they come from a different planet. When Max is exposed while saving Liz's life, a girl who attends their high school, it eventually leads to a few others learning their secret. The three aliens and their new friends try to go about their normal lives while trying to discover more about where they come from and how to get home - all while keeping their identities secret from the rest of the world.