See How They Run ending explained: Who was the murderer?

The film also boasts an incredibly starry cast, including Adrien Brody, Sam Rockwell and Saoirse Ronan, while a whole host of British stars such as David Oyelewo and Ruth Wilson serve as potential culprits when the murders begin.

Of course, any murder mystery worth its salt needs a satisfying denouement – and if you need some help recapping the events in the final scenes of See How They Run, you can read on to have the ending explained.

And of course, there are major spoilers for See How They Run below – so tread carefully.

See How They Run ending explained

After Inspector Stoppard (Rockwell) and Constable Stalker (Ronan) go through a list of various suspects – with Stalker even suspecting Stoppard himself might be behind the killings for a while – the killer is finally revealed when several of the suspects each receive an invitation to the home of none other than Agatha Christie herself.

John Woolf (Reece Shearsmith), Dickie Attenborough (Harris Dickinson), Petula Spencer (Ruth Wilson) and Sheila Sim (Pearl Chandha) are among those to be invited, only when they arrive it turns out Christie actually hadn't invited them at all, and someone else was in fact behind the invitations.

That person, it turns out, was Dennis the Usher (Charlie Cooper) who soon arrives on the scene and forces them all to gather in the drawing room, armed with a gun.

At this point, Dennis reveals that he was the real boy on whose case The Mousetrap was based and that he couldn't bear seeing his traumatic story exploited for profit. He'd killed Leo Köpernick in an attempt to stop the production, and when that hadn't worked out, he killed Mervyn Cocker-Norris as well, disgusted with the changes he'd made for the planned screen version.

Now, he had one final target: Agatha Christie herself. At this point we notice that he has dragged in a rolled-up carpet with him and that there is a person inside – only it turns out that due to a case of mistaken identity, it's not Christie but Edana Romney (Sian Clifford).

The real Christie (Shirley Henderson) is in the adjoining kitchen and has heard what's going on – and is now preparing tea for the group, applying poison to one of them intended for Dennis.

Speaking of Dennis, the group has managed to calm him down, for now, and Christie soon arrives with the teas - although unfortunately they get mixed up and her butler Fellowes (Paul Chahidi) ends up drinking the one intended for Dennis, collapsing in the process.

Meanwhile, Stoppard and Stalker have both worked out who was responsible for the murder and are both driving to Christie's house, albeit separarately since Stoppard had instructed Stalker to stay put.

Stoppard arrives to absolute carnage, with Dennis now trying to finish off Christie once and for all, while Sheila even chucks a Molotov cocktail to throw him off his stride.

In the mayhem, Dennis tries to shoot Stoppard but Stalker arrives on the scene just in time, diving in front of him and seeming to take the bullet for herself (although it is later revealed that Stoppard still got the brunt of the bullet).

Just then, Christie sneaks up behind Dennis and finishes him off herself, beating him rather viciously with a shovel and ensuring that there will be no further murders.

"A murder and a big explosion," one of the characters then muses, "Just as well Mervyn wasn't alive to see it!"

In the final moments, we find out what some of the characters got up to afterwards. The recovered Stoppard and Stalker both receive commendations before they head to watch The Mousetrap themselves, hopefully not interrupted by any real murders this time.

The very last thing we see is Stoppard turning to the camera and, in the tradition of The Mousetrap, instructing the audience not to give away the secret as they are now accomplices to murder. So whatever you do – be careful not to discuss this ending too loudly when you're out and about!

See How They Run is out in UK cinemas now. Check out more of our Film coverage or visit our TV Guide to see what's on tonight.

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