The Decoders series does not have a new book coming out soon. The latest book, The Secret of the Lady Ghost (Book 2), was published in December 2013.
The first book in The Decoders series, The Decoders in the Magic Sapphire, was published in March 2013.
The Decoders series primarily falls into the Mystery genre. This middle grade series was written for ages 8-12, but can be enjoyed by older readers as well.