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.
--Booklist Online
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.
--Kirkus Reviews
Ruby will appeal to young readers who like their action with a dash of danger, and their heroines witty and independent.
--VOYA