Dawk and Hype are lucky: they get to travel back in time from the twenty-fifth century because their parents are research scientists. Alchemist explores the world of alchemy in seventeenth-century Prague; Dragon brings the siblings together with dragon-obsessed naturalist Pliny the Elder in Ancient Rome. Undeveloped protagonists aside, plenty of historical facts complement the action in these adventures.

Two free-range 25th-century children get into and out of pickles while tagging along with their research-scientist parents to various past eras. In this series opener, a prank involving Hannibal's elephants and a mouse lands the Faradays in hot water with their employer, the Cosmos Institute. They are consequently sent for punishment to 1648 Prague to educate Holy Roman Emperor Ferdinand III about fashions in footwear. Instantly bored for understandable reasons, teenage sibs Dawkins and Hypatia fall in with Jan Richthausen, an alchemist who actually can turn mercury into gold--using found technology more advanced than the Faradays' own. Somebody is meddling dangerously. In sharp contrast to most authors who try their hand at time-travel tales, Seven has plainly thought out consistent and (reasonably) plausible ways for his characters to interact with the past without causing paradoxes or catastrophic changes to the future. Though everyone in every era speaks the same colloquial English and the source of the futuristic devices and substances is never revealed in this setup episode, the author does propel Dawk, Hype and his other lively characters through a rousing multicentury chase that loops back around to close with tantalizing hints of adventures to come. A flying start for a series that puts in a strong bid for Magic Treehouse grads. (Science fiction. 10-12)

Gr 4-8 One of the advantages of having parents who are temporal researchers for the Cosmos Institute in the 25th century is the chance to join them during field research. One of the disadvantages is having to explain nearly derailing Hannibal's march across the Alps due to a mouse, a herd of elephants, and a squeamish Carthaginian soldier. On probation after the rodent mishap, teenagers Dawk and Hype are sent with their parents to Prague in 1648 to research the footwear of Holy Roman Emperor Ferdinand III. They meet Richthausen, an alchemist who seems able to actually transform metal into gold. The siblings, along with their OpBot Fizzbin, suspect that he has come across technology from far in the future. Posing as the man's new apprentices, the teens find themselves embroiled in a dangerous mystery. The novel is light on character development but full of action and intriguing concepts and possibilities. The requisite technology of the 25th century is quickly explained in the early chapters, including the NeuroNet, which allows everyone access to all the world's compiled knowledge, and the Link, its social component. The short chapters may appeal to reluctant readers. This sci-fi foray is sure to be embraced by kids who once relished the time-traveling adventures in Mary Pope Osborne's "Magic Tree House" series (Random) or Jon Scieszka's "Time Warp Trio" (Penguin) and those who enjoy the "Infinity Ring" (Scholastic) series. Amanda Raklovits, Champaign Public Library, IL