Perhaps the Morgan children would never have met Phyllida and Lysander Asher, their distant English relatives, were it not for the epidemic that threatened America. Afraid for their children, college professors Tom and Glynis Morgan ship their children off to England.
For Rowan, Meg, Priscilla, and James Morgan, life with the Asher's seems like it could be ideal. The house, officially named "The Rookery", is enormous, with lots of places to explore, and a fabulous garden just outside the house. The only downside to their stay may be the last-minute additions of two boys, both of them sons of other college professors: Finn Fachan, an annoying boy that the four Morgans despise equally, and Dickie Rhys, a bookish boy that the Morgans mostly ignore.
The Ashers are pleasant old people. However, they have some very strange rules. The children wonder, why is the forest forbidden? Why can't they give their names to strangers? And why mustn't they accept food from anyone?
Very soon, the Morgans discover the reason. They have arrived in England on May Day, and when they ignore the Ashers' warnings and venture beyond the grounds on the first night of their stay, they come upon the Green Hill, threshold of the Seelie Fairy queen's domain. There, Rowan is chosen to be the Queen's champion in the Midsummer War, a battle fought between the two opposing fairy courts, Seelie and Host. Rowan is their human champion. He must fight the Host's human champion, and either he or his opponent must die.
Determined to save her brother, Meg vows to do all she can to prevent Rowan from fighting in the battle. When she discovers that, without the spilling of the blood of mortal man the land will die, Meg is in a quandary. Can she justify preventing the War to save her brother if it means destroying England?
This was a very gripping story. Laura L. Sullivan draws heavily on Celtic and Arthurian legends to create a story that is as real and believable as the sun outside.