As if traveling to a new country in search of her missing mother weren't difficult enough, Mira has to do it dressed as a boy. In a different century. A new postcard from her time-traveling mother points Mira to the 16th century Rome. But before she can rescue her mom, she must follow the clues left around the city to find Giordano Bruno, a famous thinker and mathematician, who discovered something so shocking that important Italian officials don't want it revealed. All the while avoiding the Watchers-time-traveling police who want Mira back in her own time. It's another whirlwind adventure for Mira, and this time she is determined to bring her mother out of the past.
