El Capitan Calzoncillos y el terrorifico retorno de Cacapipi:

Tra-la-laaa! Captain Underpants is back in an all-new epic adventure that's the zaniest, funniest, outrageousest, and time-travelingiest yet!In this ninth epic novel, Dav Pilkey takes readers back in time to the carefree days of kindergarten, when the worst thing George and Harold had to face was NOT evil mad scientists or alien cafeteria ladies but a sixth-grade bully named Kipper Krupp, the nephew of their school principal. And because George and Harold don't actually invent Captain Underpants until fourth grade, the two clever kindergartners are on their own -- using their brains to beat the bully.En la novena novela, Dav Pilkey lleva a los lectores a los tiempos en que Jorge y Berto estaban en kindergarten, cuando la mayor preocupación de los chicos era un abusón de sexto grado sobrino del director de la escuela.