Alex Scarrow 
TimeRiders: The Doomsday Code (Book 3) 

Liam O»Connor should have died at sea in 1912.
Maddy Carter should have died on a plane in 2010.
Sal Vikram should have died in a fire in 2026.

But all three have been given a second chance — to work for an agency that no one knows exists.
Its purpose: to prevent time travel destroying history . . .
In 1993 British computer hacker Adam Lewis finds his name in a coded manuscript that is almost one thousand years old. How did Adam»s name get in there . . . and why?
Confronted by Adam in 2001, the Time Riders travel back to Sherwood Forest in 1193 to discover the origins of the ancient message. But when a strange hooded man appears interested in the same thing, they begin to wonder what terrible threat this cryptic link from the past holds for the future . . .