Packed onto the overnight Glasgow to London sleeper, a cross section of passengers settle in for the long ride ahead. But their journey quickly takes an alarming turn when unknown hackers gain control of the train, cutting it off from the outside world. Now, without cell service or any way to communicate with the driver, those on board face an uncertain fate as the train hurtles ahead under new management. Former cop Joe is thrust into a leading role as the only one who seems willing to take charge. He works with cyber expert Abby back in London to discover who’s truly at the controls and how to stop a hijacking that may spell disaster for Britain’s entire rail system.

This is the premise that launches BBC’s latest mini-series thriller, Nightsleeper. Six tense episodes follow the cliffhanger format of hits like 24 as passengers and authorities race to...