Perhaps it all started when a kind stranger helped Rachel to board the Kindertransport in 1939, or in 2025 when scientists Jamie and Annamarie accidentally invented a time portal.

Or maybe when Jamie's mother Fran, the only historian they could trust to keep their secret, persuaded them to let her investigate an ancestral mystery in person. But now Annamarie is missing in Nazi occupied Prague, and Jamie must arrive on time to undertake a desperate rescue mission.

Meanwhile, four-year-old Freddie, grandson to Fran and nephew to Jamie, struggles with vague memories of a time before he was born, and a deep sense that his grandmother is in danger. When Annamarie fails to return from her trip through the portal, all play crucial roles in an initial attempt to recover her. As events unfold, it falls to Jamie to undertake a dangerous mission to Nazi-occupied Prague to arrive on time to ensure that Rachel boards the train to her destiny in England, to maintain the integrity of the timeline.

As each character in succession becomes embroiled in their own ancestral issues, they are buffeted by events relating to the Scottish diaspora, Scottish Presbyterianism in the late nineteenth century, the Battle of the Somme, the Kindertransport of 1939, the Czech resistance movement of World War II, the Californian hippie culture of the 1960s, the Prague Spring of 1968 and their families' geographical transience in time. As their adventures unfold, they begin to understand their immersion in history, through deep and enduring emotional connections between generations, transcending time and location.