Sometime in May
Yes there is. At the end of the book Double Cross it says "more in... Hit Squad" meaning there is going to be a sixth medusa project book. Thus book is going to be released around March 2012. However Sophie Mckenzie said that Hit Squad is going to be the final book and she is thinking of writing it from a varied perspective but is still unsure. I hope this was helpful to many people :)
A Double Double Cross - 1916 was released on: USA: 23 August 1916
Cross Hair Double Cross - 2010 was released on: USA: 7 December 2010
The Double Cross - 1912 I was released on: USA: 23 July 1912
Double Cross - 2013 was released on: USA: 5 September 2013
Double Cross - 1931 was released on: USA: 5 July 1931
Double Cross - 1941 was released on: USA: 27 June 1941
Double Cross - 2010 was released on: USA: 26 March 2010 (internet)
Double Cross - 2011 was released on: USA: 23 August 2011 (internet)
Jerry's Double Cross - 1917 was released on: USA: 20 December 1917
Cross is played by Dean McKenzie in Need For Speed Most Wanted
Black Gold - 2008 Double Cross was released on: USA: 16 January 2013