The BBC's Nightsleeper is hoping to park in the sadly vacant spot left by Sherwood (we're still bereft). And when it comes to Sunday night 9pm dramas, the Beeb usually nails it.

This time, though, we're getting something a little bit different. Nightsleeper is a real-time thriller for BBC One and iPlayer. Like the hugely successful (and, at the time, groundbreaking) US drama 24, and last year's Hijack on Apple TV+, Nightsleeper plays out in real time.

Here's everything you need to know about the upcoming BBC One thriller Nightsleeper, including start date, cast, and twisty plot.

What's the plot of BBC One thriller Nightsleeper?

BAFTA-winning writer Nick Leather created this new action thriller which follows a train after it's "hackjacked". The train is driven through one single night from Glasgow to London, with everyone on board in serious danger.

But who has taken control of the train via hacking, and why? And can have-a-go hero Joe Roag - a cop who just happens to be a passenger - attempt to save the day?

The BBC describes the new series as "part fast-moving heart-in-mouth action-adventure and part twisty-turny whodunnit detective story".

They tease that the series "promises to be a roller coaster drama where no-one is ever quite who they seem".

Sounds intriguing - we're in!

Cop Joe Roag must work alongside stranger Abby Aysgarth, the acting technical director at the National Cyber Security Centre (NCSC). But who are they fighting? And how can they stop the train against the driver who seems to be constantly one wheel ahead?

How many episodes is Nightsleeper?

Nightsleeper on BBC One is six episodes. Each episode is one hour long.

The entire six-hour series will play out in real time over the time (roughly) it takes to get from Glasgow to London.

Who's in the cast?

Like Sherwood before it, Nightsleeper has a great cast. Peaky Blinders actor Joe Cole recently proved he can do action hero when he portrayed Harry Palmer in ITV's adaptation of The Ipcrss File.

This time, he portrays off-duty copper Joe Roag, who leaps into action when the train he's on is cyber-hacked.

Sandition actress Alexandra Roach portrays Abby Aysgarth, the acting technical director at the National Cyber Security Centre (NCSC). She teams up with Joe - albeit by phone - to help stop the train hurtling to destruction.

Shameless favourite David Threlfall portrays Paul Peveril, while London Kills star Sharon Small plays Liz Draycott.

TV faves Sharon Rooney, Katie Leung, Alex Ferns, James Cosmo, and Ruth Madeley also appear in the great ensemble cast.

What's the start date of Nightsleeper? How can I watch?

All episodes of Nightsleeper go up on BBC iPlayer at 6am on Sunday, September 15, 2024.

BBC One will show episode one at 9pm that same Sunday, with episode two following on Tuesday. The series will air over three weeks on Sunday and Mondays.

Nightsleeper streams on BBC iPlayer from 6am on Sunday, September 15, 2024.