Set on a train from Glasgow to London, a government agency intervenes in escalating events onboard. Two strangers work together to save passengers as the train hurtles towards disaster.

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?