Johnny Maxwell, earnest English lad, and his friends take on the tricky ethics of time-travel paradox in this, the concluding volume of The Johnny Maxwell Trilogy. Seems Johnny’s been researching WWII for school, and when the local bag lady’s shopping cart sends him and his cronies back to a critical moment, he needs to decide whether to warn the town of an impending Luftwaffe raid and change history or let the unaware residents of Paradise Street die. Pratchett being Pratchett, of course, this inquiry into the Butterfly Effect comes replete with giggles, from the antics of the hapless Bigmac (who nearly derails the mission when his WWII-era costume turns out to be a salvaged German uniform) to the kids’ reappearance into modern times in a church basement during the Over-50s Keep-Fit class. Chuckles aside, it’s Johnny’s agony at the human suffering of the world that cuts to the bone and will keep readers tracking the moral debate at the core of the novel, as the always-angry Kirsty hews to theoretical absolutes while the always-worried Johnny grieves the world’s madness. Complex, funny and, above all, impassioned. (Fiction. 10-14)