Kan det vara Assassins dag av Johnny O "Brien, från 2009?
Per Goodreads:
Jack Christie and his best friend, Angus, find themselves at the center of a momentous event that will shape history for decades to come. Their dilemma: Should they intervene? Their problem: Can they survive? Join Jack on a dangerous chase from the dockyards of England to the rain-sodden trenches of the First World War. Will he escape the evil authorities who believe in the mysterious Vigil Imperative?
utgivarens webbplats har en liknande blurb, men också inklusive:
When teenager Jack Christie stumbles upon a time machine and a secret time-travelling society his life changes forever.