Pilkey took a break from writing for a few years to care for his terminally ill father (who died on November 13, 2008), but in 2009 agreed with Scholastic to publish four new books. The first two are graphic novels: ', released on August 10, 2010; and ', released on June 28, 2011. "Captain Underpants and the Terrifying Re-turn of Tippy Tinkletrousers" was released on August 28, 2012 and "Captain Underpants and the Revolting Revenge of the Radioactive Robo-Boxers" was released in January 2013.