Seventh-grade sleuths visit their local libraries and unmask a Russian spy ring.
When a chance discovery heats up a cold case, Florian and his associate, rival, and best friend, Margaret, follow their beloved FBI contact Special Agent Marcus Rivers as he revisits old Washington, D.C., sites and suspects—and then suddenly find themselves in a race against time to prove that evidence implicating Marcus in the espionage was planted. The investigation revolves around books and libraries, as all of the major suspects are current or former library workers (and, it turns out, the spies communicate with a complex but plausible code using Dewey Decimal numbers). Ponti does his homework with commendable thoroughness and, aside from the occasional infodump, presents creditable inside views of both local branch libraries and larger institutions including the Folger Shakespeare Library and the Library of Congress. Narrator Florian is white; thanks to a DNA test, African-American Margaret, who is adopted, discovers that she has both African and European antecedents, which triggers a short but thoughtful discussion of identity; and Marcus, African-American, leads a similarly diverse supporting cast. The pleasures of watching the young sherlocks once again deduce rings around the grown-ups (using a technique they call TOAST, for “Theory of All Small Things”) are just as rich in this trilogy closer as they were in Volume 1.
A top-shelf test of courage, friendship, and ingenuity. (Mystery. 11-13)