Journey through one family's turmoil caused by an unexpected move and a sick child. The author tells the true story of daughter Rebecca's mystery illness and the back-story of the family's move to Florida in a direct, humorous style. The book includes interviews with experts in medicine and psychology. Although Rebecca's problem was physical, there was also an element of depression brought on by the twelve-year-old's fear that no one believed her pain was real. Even more bizarre was the fact that the child named her pain "Earl" and dealt with it as though it was an assailant.
 

Rebecca's mystery illness affects over 86,000 American children each year, and up-to-date information about medical treatment is included in the text. As she wrote the book, the author confronted fears about her children, fears that began in her own childhood with the death of her infant brother who died from an undiagnosed illness. Day wrote Killing Earl at the request of her daughter who says, “I hope nobody ever has to deal with an Earl.