The Gemma series does not have a new book coming out soon. The latest book, The Treasure Hunt with Griffin (Book 2), was published in November 2012.
The first book in the Gemma series, The Search for the Gem, was published in August 2011.
The Gemma series primarily falls into the General Fiction genre. This middle grade series was written for ages 8-12, but can be enjoyed by older readers as well.