After grrowing up in Roswell believing they were the only aliens on Earth, Max, Isabel and Michael are still struggling to acccept Tess, another alien who claims to have originally arrived on the planet with them. Her revelation that she and Max are destined to be together and that Isabel and Michael are likewise destined continues to be painful for everyone involved, especially for their human friends Liz, Maria and Alex. Yet even as the group bands together to battle a new alien threat, the mysterious death of Alex leads Liz and Maria to suspect there's an even more deadly enemy amoung them--one with a secret agenda that could alter their lives forever.