Gr 4–7 —Dan and Amy Cahill, a pair of orphaned siblings with white skin and red hair, find themselves in a dangerous world of adventure when their beloved grandmother Grace passes away, leaving a potentially massive inheritance to those willing to solve the mystery of the 39 clues. As the siblings find out, the Cahill family is one of the largest and most influential families in all of history, with members ranging from Benjamin Franklin to Louis Armstrong. If they are able to solve the treasure hunt, they will become the most powerful people on the planet. They're not alone in their quest, however, and their competitors are made up of distant members of their family of varying skin tones and ages. Luckily they're smart, and they have help in the form of their au pair, Nellie, who has brown skin and green and pink hair, and their grandmother's beloved cat, Saladin. Along the way, readers will learn a little bit about history, though it may be hard for some readers to parse what is real and what is invention. The character of Nellie does border on the trope of a BIPOC employee becoming a member of the family, and she does not get fleshed out much; readers may wonder if she has any family or connections outside of these children. The book moves quickly, aided by colorful and lively illustrations, and captures readers' attention from the start. VERDICT Sure to attract new readers and maybe some returning fans, this will likely be very popular and should be a first purchase for most collections.—Kadie Seitz