It’s as if James Bond met Nancy Drew met Harriet the Spy, and it works most effectively, complete with appendixes that discuss code breaking in music, text, and graphics. Three cheers for a determinedly wholesome mystery series that doesn’t talk down to its tween audience.
Ruby is a smart, feisty, and definitely fun character who easily pulls readers into this fast-paced mystery. There are a variety of secret codes throughout the book that readers can have a go at in the concluding section. While this is the second title in the series, it can definitely stand alone, although readers will surely want to read more about this spunky character’s adventures.
—School Library Journal
The codes (musical and binary) that Ruby deciphers are great fun... [A] middle-grade mystery for budding sleuths.
Ruby will appeal to young readers who like their action with a dash of danger, and their heroines witty and independent.