X-Men meets Spy Kids in the fifth installment of The Forgotten Five middle-grade fantasy/adventure series by the New York Times bestselling author of The Unwanteds.

The Forgotten Five and their friends are reeling in the aftermath of the raid on Magdalia Palacio's campaign rally—an attack masterminded by her corrupt opponent President Fuerte and his henchmen. Birdie is in the hospital with a head injury, and under arrest for stealing a police horse in her attempt to evade capture. Separated from her friends—and not even allowed to see her mother—how can Birdie escape when she is utterly alone?

Then the Librarian is taken captive in the heavily guarded palace dungeon after Fuerte discovers she's been acting as a double agent. What will they do without their trusted mentor?

Luckily, the five have been honing their supernatural abilities, and it's Brix who takes the lead, forging an unlikely alliance and putting together a plan. Does the group have what it takes to rescue their friends and even the odds in the president's all-out war against Estero's supernaturals?