The Mysterious, Mournful Maiden (Princess Power Series #4)

Princess Elena is delighted to find a treasure on the seashore—a beautiful comb that tames and softens her frizzy hair. However, she soon starts dreaming of a green-haired maiden who cries that she can't live without her comb. The princesses all want to help. But will they be able to find the maiden before it's too late?