A Knotty Problem... Meg Whistowe, a midwife, witch, and amateur sleuth, lives in a medieval Yorkshire village. Weary of her workload, she takes on an assistant, Mattie, a sassy, clever 15-year-old.
A body with an unusual ring on its finger is discovered in the forest by a curious pig. Unable to resist a mystery, the two, plus Meg's telepathic cat, Bea, follow the ring and travel back in time to Windsor Castle in 1421, unaware that the body was deliberately placed there to lure them.
At Windsor Castle, Queen Catherine de Valois, the French wife of King Henry V, is about to give birth, anxiously awaiting her midwife. Meg arrives just in time, not realising she is part of a diabolical plot. If the queen bears a son, the new prince will become heir to both France and England.
Someone in the castle with magical powers plans to prevent this, aided by a sorcerer who wishes Meg serious harm. Mistress Meg and Mattie must use all their skills to deliver the royal baby, discover the plotters, navigate Windsor Castle, including the dungeons, and stay alive.