The Princess, the Crone, and the Dung-Cart Knight (The Squire’s Tales #6) by Gerald Morris
Meet thirteen-year-old Sarah, who has been living on her own and searching for the knight who was responsible for her mother’s death. Her quest for revenge leads to an even greater adventure when she witnesses Queen Guinevere being kidnapped. Soon Sarah finds herself accompanying Sir Gawain and Squire Terence on a remarkable journey to rescue the queen. Join Sarah on her inspiring quest to avenge her family’s death.