George and Harold link up in kindergarten to reduce a quartet of vicious bullies to giggling insanity with a relentless series of pranks involving shaving cream, spiders, effeminate spoof text messages and friendship bracelets. Cut to five years previous, in a prequel to the whole series. The villain sets off after George and Harold, who are in juvie (“not much different from our old school…except that they have library books here.”).

There, he witnesses fellow inmate Tippy Tinkletrousers (aka Professor Poopypants) escape in a giant Robo-Suit (later reduced to time-traveling trousers). To start, in an alternate ending to the previous episode, Principal Krupp ends up in prison (“…a lot like being a student at Jerome Horwitz Elementary School, except that the prison had better funding”). Not that there aren’t pranks and envelope-pushing quips aplenty. Sure signs that the creative wells are running dry at last, the Captain’s ninth, overstuffed outing both recycles a villain (see Book 4) and offers trendy anti-bullying wish fulfillment. Will appeal to readers who appreciate action-oriented tales. Also, his multilingual, ethnically ambiguous protagonist is so much smarter and more competent than any of the grown-ups that none of the pickles she gets into are more than briefly suspenseful. Though-except for the paucity of high-tech gadgets and a refreshing centering of a highly competent girl hero-comparisons with the Alex Rider series are almost inevitable, the author’s fondness for overexplaining never lets the pace build up a compelling head of steam.

What might the “Greatest Treasure” be? Gibbs plays his cards close to his chest as he employs multiple point-of-view characters to spin out a chase through crowded city streets and teeming tropical forests, punctuated by big explosions and hails of gunfire, to a climactic flurry of lurid fatalities. Holed up in the Galápagos Islands and hotly pursued by both the CIA and the KGB for knowing Einstein’s most deadly secret (see Charlie Thorne and the Last Equation, 2019), Charlie decodes a message about the “Greatest Treasure in Human History,” carved by Darwin almost two centuries ago on a tortoise’s plastron, and follows further coded clues first to Quito and then on into the Peruvian wilderness-with, eventually, no fewer than four sets of secret agents and treasure hunters in her wake. Hints left by Charles Darwin of a world-changing discovery send a 12-year-old supergenius deep into the Amazonian rainforest.

Charlie thorne and the lost city