When Liz Ortecho is shot at her parent's diner, the Crashdown Cafe, Max Evans uses his alien powers to heal her. Liz and her best friend Maria DeLuca are amazed to discover that Max Evans, the human-looking kid they had gone to school with almost all their lives, is an alien. Unable to hide anything from Liz, Max reveals that his sister Isabel and their best friend Michael Guerin are also aliens. Without any idea of what planet they are from, or why they are on Earth, the three alien teens are living normal lives in Roswell, New Mexico.
After the shooting and healing at the Crashdown Cafe, Sheriff Valenti is hot on the trail of the alien teens. Max's sister Isabel is worried and scared. Maria is just as frightened. Turning to her best friend Alex Manes, Maria spills the secret of the aliens, and the group of six teenagers--some alien and some human--must pull together to stop Valenti, an alien hunter from a government agency called Project Clean Slate from discovering Max's secret.