Four detectives. Four timelines. One body. To save Britain's future, they'll need to solve the murder that altered the course of history first.

On the rugged isle of Berk, where Vikings and dragons have been bitter enemies for generations, Hiccup stands apart, defying centuries of tradition when he befriends Toothless, a feared Night Fury dragon. Their unlikely bond reveals the true nature of dragons, challenging the very foundations of Viking society.

Set on a sleeper train traveling from Glasgow to London, a government agency desperately tries to intervene in the rapidly-escalating events onboard. Can two people who’ve never met, one on the train and one not, work together to save the lives of its disparate group of passengers as the Heart of Britain service hurtles towards what might quite literally be its final destination?