Meg and her siblings have been sent to the English countryside for the summer to stay with elderly relatives. The children are looking forward to exploring the ancient mansion and perhaps discovering a musty old attic or two filled with treasure, but never in their wildest dreams did they expect to find themselves in the middle of a fairy war. When Rowan pledges to fight for the beautiful fairy queen, Meg is desperate to save her brother. But the Midsummer War is far more than a battle between mythic Everything that lives depends on it. How can Meg choose between family and the fate of the very land itself?

Only a few weeks ago, Meg Morgan and her siblings went to England for the holidays—and found themselves in the middle of a fairy war. Now the war is over, but the battle for control of the fairies has just begun. A mysterious painter named Gwidion appears at the Rookery, ready to give the children art lessons. But his real plans are far more sinister: He means to destroy the Guardian of the Green Hill, the woman who keeps the peace between fairies and humans. Meg knows nothing of the evil artist's plans, but she is beginning to understand that she might be the only one who can become Guardian when her great-great aunt's time is over. Yet Meg is just a girl—surely she has plenty of time before she must decide whether she wants to take on such an enormous role. Then someone she loves is stolen by fairies, and no one but Meg can get him back...