Allen Strange is having a split personality problem -- literally! After a near-miss with a car, Robbie Stevenson ends up with Allen on the curb...while her brother, Josh, is across the street with Allen's pure alien form. Allen's thrilled. He's a twin. Now Allen can experience life as a real human being while keeping tabs on Alien through their strong mental connection.
It's not long before Allen discovers that life as a human is harder than it looks. He can't speed-read books. Earth math no longer seems primitive. And it's tough work setting up for a school show without his powers. But that's not what worries Allen. He's feeling very sick...and he's lost the connection with Alien.
Meanwhile, Alien's having his own problems. He's on the run from Phil Berg, the alien hunter. Now, Robbie and Josh must figure out how to recombine Allen's two halves...but can they track down Alien before it's too late?