THE HERO ENGINE

After her adopted grandfather’s visionary weapons plans are stolen, a teenage girl joins forces with a soldier’s son to save the Roman Republic in this YA alternate-history novel.

In the year 79, 13-year-old Petra goes aboard an arriving ship to get available scrolls to copy for the Library of Alexandria. To her shock, the scrolls are plans for innovative weapons—the work of her adopted grandfather Hero. Cassius, a Roman officer who had tried to get these plans from Hero, must have stolen them. Petra and Hero travel to Pompeii to alert Pliny that Cassius, trying to put a new “false Nero” in power, has this military advantage. Upon arrival, Petra meets Pliny’s nephew, Gaius, a boy around her age whose father, Lucius, has been captured by Cassius’ forces. Gaius and Petra sneak into the coliseum to help Lucius fend off a mechanical gladiator and other dangers. Hero also deploys the nimble teens to drop into Cassius’ weapons factory. Afterward, as Petra and Hero depart for home, they discover that Vesuvius is about to erupt and that Cassius has a special new battleship. Petra and Gaius employ other intriguing contraptions before the story’s end. Over the course of the novel, Cooper provides an engaging spin on history that leverages some real-life historical figures (Hero, Pliny, and others) and almost nonstop action. The coliseum scene is a tour de force, with the teens filling it with water (as was sometimes done in ancient times) and facing a wonderfully realized “wall of death” of mechanized weapons. Cooper also includes some lovely moments in which the teens consider giving in to rage (“No revenge is worth our lives”) or flirt with each other. Although the revelation of Petra’s identity feels a bit rushed, it also tees up future exploits featuring the charming, intelligent main character.

An exuberant high-tech ancient-world adventure.