The Doomsday Code — Alex Scarrow

When a British computer hacker finds his name coded into a centuries-old manuscript, TimeRider Maddy recognizes it as the same message she had also been sent. Sure it must be communication from other TimeRiders agents, she sends Liam and the two support units back to Robin Hood's time to search for the fabled document-possibly the Holy Grail. But as a war begins to brew between King Richard and his brother John, Liam unwittingly takes on the role of the Sheriff of Nottingham and discovers that the mythical Robin Hood may have been another support unit all along. This action-packed reimagining of the Robin Hood legend, weaving elements of religion, alternative history, and time-travel ethics perfect for fans of The DaVinci Code, is a page-turner old fans and new ones alike won't want to miss.