When Mama's purse falls on the floor, Sofia gets a peek at Mama's old Resident Alien card and comes to the conclusion that Mama might be an alien from outer space. Sofia heads to the library to learn more about aliens. Some are small and some are tall. Some have four fingers on each hand and some have large, round eyes. Their skin can be gray or blue or green. But Mama looks like a human mother! Could she really be an alien? Bilingual English/Spanish