Billy Smith is a typical teenage boy.He has many friends who he would rather hang out with than babysit his two kid sisters;Molly and Carol Anne.One night, Billy's parents go out to dinner and leave him in charge of his baby sister; Carol Anne.At first, he thinks that this'll be another boring Saturday night of babysitting, but tonight will be anything but.Just as Billy puts his baby sister;Carol Anne to bed in her crib, a port-hole into another dimension...