The Pimpernel Plot (Time Wars) by Simon Hawke

Pre-oved Paperback Time travel wasn't just fun and adventure. Major Lucas Priest, a veteran of the Time Wars, was aware of the danger of operating in Minus Time. One false move, and the course of history is changed with incalculable consequences. Now Lucas is faced with the greatest challenge of his career: to readjust the events of the French Revolution and correct the blunder made by an agent of the Temporal Corps. Alex Corderro, in his first hitch in Minus Time, had caused the death of Sir Percy Blakeney, the English aristocrat who played a key role in saving French royalists from the guillotine. Someone had to impersonate Blakeney and carry out his task. Easier said than done. Especially since the much-feared Mongoose, that great saboteur and double agent from the 27th century, was on the loose again. And Mongoose had other ideas of how history should proceed . . .