'Knives Out' Ending Explained: Who Killed Harlan Thrombey?

Knives Out is a movie that delights in confounding an audience's expectations of what a whodunnit should be. So of course when Benoit Blanc (played by Daniel Craig) finally gets round to revealing the culprit of the central murder, things are far more complicated than discovering which member of the all-star cast slit Harlan Thrombey's (Christopher Plummer) throat. Instead, it turns out that all the clues have been hiding in plain sight, and that, perhaps unlike any mystery movie before it, the initial theory turns out to be totally correct.

WARNING: Spoilers for the entirety of Knives Out below

Harlan Thrombey died of suicide by slitting his own throat, just as the police first ruled.

However, of course things are more complicated than that, thanks to the joint efforts of Harlan's grandson Hugh 'Ransom' Drysdale (Chris Evans) and Harlan's nurse Marta Cabrera (Ana de Armas). Of these two, the one who we think is innocent turns out to be the murderer (or, at least, the attempted murderer), while the one we think is the murderer turns out to be perhaps the only totally innocent person in the entire movie.

A recap of the first explanation we get of Harlan's death, which comes about a third of the way into the film. In trying to give Harlan his nightly pain relief, Marta accidentally switches the bottles, giving him what she thinks is a lethal dose of morphine. In order to protect Marta from getting punished for this mistake, Harlan has an idea.

He gets Marta to make his death look like a murder from one of his murder mystery books, throwing the scent off of her and onto the rest of the Thrombeys. He then slits his own throat to make it look like he has been murdered, hoping that the police will be so busy choosing between the many suspects they will not notice the morphine in his blood.

knives out ending explained
Benoit Blanc (Daniel Craig), explaining the ending of "Knives Out" Lionsgate

After all, most of them have a reason to kill the family patriarch after he tells them he will no longer financially support them after his 85th birthday party⁠ (this is because, as they will find out after he dies, he has changed his will to give everything to Marta).

This plan, however, is complicated when someone who has stolen her medical bag and has the toxicology reports from Harlan's corpse starts blackmailing Marta. Or so we think.

At this point, we need to consider the role of Ransom in all of this, for it is really him who is being blackmailed. Why? Because he had previously that night swapped Harlan's medications, hoping that Marta would therefore unwittingly cause him to overdose on morphine, making her his killer and therefore making the will (which Harlan had told him about at the party) null and void.

However, being the excellent nurse that she is, Marta had given the right medication, which she knew by touch⁠—it is only after she reads the switched label that she thinks she has killed him.

harlan thrombey knives out
The real killer of Harlan Thrombey (Christopher Plummer) in "Knives Out" turns out to be...Harlan Thrombey Lionsgate

This means that he was never in any danger of an overdose⁠—in fact, if he had followed her advice to call an ambulance rather than cook up an elaborate plot, it would have been discovered there was no morphine in his blood and Harlan would still be alive.

This is all made even more complicated by the fact that Ransom is being blackmailed by another of Harlan's staff, Fran (Edi Patterson), who has an inkling that he switched the medications. However, Ransom then uses Fran's blackmail note to pretend to blackmail Marta to get her to go to the meeting place where he is to meet Fran. He kills Fran and frames Marta for the murder after he reads the toxicology report and discovers that she had not delivered a lethal dose of morphine to Harlan as planned.

However, we do not initially know Fran is dead, allowing Knives Out to get one last twist in there. While Benoit (who to make things even more complicated was hired by Ransom as part of his plot to frame Marta) explains exactly what has happened, Marta receives a phone call from the hospital about Fran, and she lives and tells everyone she is alive. This causes Ransom to gloat and admit to his misdeeds, thinking that the worst crime he has committed is attempted murder, which he believes his lawyers can quash as a conviction.

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Ransom (Chris Evans) is the closest thing "Knives Out" has to a killer Lionsgate

Of course, Marta has a condition whereby she cannot lie without vomiting, so we soon know she has not been truthful when she delivers a face full of sick all over the one-time Captain America. Finding out he has been recorded by the police making his confession, Ransom attacks Marta with a knife that is part of Harlan's ring of knives. However, as alluded near to the beginning in a conversation between Haelan and Marta, the house is full of prop, retractable stage knives, one of which he has just used fruitlessly to try and kill her.

The film then ends with Ransom being taken away while the rest of the Thrombeys are outside of the house now owned by Marta, with the rest of the cast as confused to what's happened as many viewers of Knives Out will be by its twisty, ever-shifting plots.

Knives Out is in cinemas now.