Exiles in Time

Two years in Afghanistan; four years working for MI-5, the British security service; and the death of both of his parents from cancer. At the age of thirty-four, Callum thought he'd experienced the worst that life could throw at him. That is, until his boss ordered him to open a buried file on his desk and to take it seriously. His new assignment: to detain and question a pregnant woman and her ailing husband—and if need be, to stop them from returning to medieval Wales.
Until today, Callum believed in his job and always followed orders. Until today, he thought time travel wasn't real …
Complete Series reading order: Daughter of Time, Footsteps in Time, Winds of Time, Prince of Time, Crossroads in Time, Children of Time, Exiles in Time, Castaways in Time, Ashes of Time, Warden of Time, Guardians of Time. Masters of Time, Outpost in Time, Shades of Time, Champions of Time, Refuge in Time, Unbroken in Time, Outcasts in Time, Hidden in Time, Legacy of Time. Also, This Small Corner of Time: The After Cilmeri Series Companion